The following are some rules I created for running Ethereal player character prior to the printing of the Ethereal Players' Guide. They're still an interesting, alternate take on the whole thing:
Ethereal player characters start out at seven forces, and have 150 essence to spend on vessels, at the costs given in The Marches (which can buy two levels of human vessels, or more levels of simpler vessels).
Ethereals don't use character points. Instead, they use essence directly to improve themselves. Ten essence equals one character point. An Ethereal can only hold essence equal to its forces, but additional essence can be stored in a cache, which may hold up to a hundred times the Ethereal's forces in essence. Essence in the cache can only be used as character points—for improving skills, songs, and stats, and for buying vessels. Forces may not be bought directly, only gained via raising stats.
Ethereals get one rite per force. These rites should define some sort of concept analogous to a Word. They need not be things the ethereal itself must do—being worshipped is a fairly common rite. (As a guideline, an ethereal may have "Have 1 person do a difficult task", "Have 10 people do a moderate task", "Have 100 people do an easy task", or a "Have 1000 people do a trivial task" as rites. Such rites may be taken multiple times, but increase the number of people involved by a factor of ten each time. Thus, some ethereal may receive 3 essence daily from having 1000 people do a moderate task; the ten and the hundred people count towards that thousand.)
Every Sunday at noon, they lose cached essence equal to their total number of forces, as their very existence requires constant fueling. If this is more than they have, it comes out of their forces (they "cash in" attribute points for 30 essence until they can pay the cost). (Thus, if an ethereal has rites that are never used and never spends any essence, it will eventually stabilize at seven forces.)
Additionally, Ethereals get one innate ability analogous to a resonance. Sample ones are:
Changing vessels does not cost a Shapeshifter any essence. Vessels cost half as much in essence to create. All the Shapeshifter's vessels heal naturally, not just the one currently in use.
Having a transformation observed by a mortal human causes the Shapeshifter to lose essence equal to its forces.
With a successful precision check, a Doppelganger may take on the exact appearance of any human (or human vessel) in sight, with the standard bonuses and penalties for touch and recorded images, etc. The check digit determines how perfect the copy is. Failing on a six means the Doppelganger may never again attempt to impersonate that individual. With a successful intelligence check, a Doppelganger may fool others into thinking it is the individual it is currently imitating; penalties apply if the person being fooled knows the individual in question well. If such a check fails with a check digit of six, the subject sees the Doppelganger for what it is, and reacts accordingly. Doppelganger vessels have no inherent appearance; they must always be imitating someone. They may buy vessels that imitate species other than humans; each vessel is good for one species, determined at creation time.
Being discovered to be a Doppelganger causes one to lose essence equal to its forces.
With a successful intelligence check, a Manipulator may read the current emotional state of a person, similar to an Elohite, though not quite as thoroughly. Once it has read this state, it may attempt to subtly manipulate the subject's emotions with a successful precision check. Existing emotions may be amplified, or new emotions may be created at a mild level; this is much less intrusive than the ability of Habbalah. Whether successful or not, the subject gets an intelligence check; success indicates that he realizes the emotion is not quite his own (though he still feels it), or that he is being manipulated. Using either ability requires interacting with the subject (i.e. speaking to him, hanging around him a while, etc.).
Angering someone a Manipulator attempted to manipulate, or having one of its schemes backfire, causes it to lose essence equal to its forces.
With a successful intelligence check, a Trickster may determine what an individual would find believable in the current situation. With a successful precision check, resisted by the intelligence of each of the subjects, a Trickster may cause them to perceive any illusion they would find believable; this may affect no more people than the Trickster's ethereal forces.
Resorting to violence when there was a way to use wits to get out of a situation causes a Trickster to lose essence equal to its forces.
Before any strength or strength-based check, a Warrior may make an intelligence check and add the check digit of a successful roll to its strength. Before any agility or agility-based check, a Warrior may make a precision check and add the check digit of a successful roll to its agility.
Failing a modified roll with a high check digit, or being defeated in combat causes a Warrior to lose essence equal to its forces.
Smiths may bond to any item as if it were a corporeal artifact by spending one essence and making a successful precision check; the level of the artifact equals the roll's check digit. Decrease its level by one every day until it is no longer an artifact. Such artifacts function only for the Smith. By spending another essence and making a successful intelligence check, a Smith may turn any such artifact into a talisman for any skill it or another individual who helps it knows; the level of the talisman is equal to the lesser of the check digit and the level at which the skill is known. Again, the level drops by one per day. The talisman may be used by anyone. By spending one essence and making an intelligence check, a Smith my turn one of its artifacts into a one-shot reliquary. This reliquary has a level equal to the check digit, and it drops by one per day. Anyone may freely put essence into and take it out of the reliquary. If the reliquary is full when its level drops, the extra point of essence is lost, generating a disturbance. By spending one essence, making an intelligence check, and performing a song, or having an assistant perform a song, a Smith may imbue one of its artifacts with a single use of that song to be used later, at the level at which it was performed. It generates a disturbance both when created and when used. Using it requires one round and a successful intelligence check. If not used, it fades after a number of days equal to the original check digit of the Smith's Intelligence check, making a disturbance when it does so. At no point may the Smith have more temporary artifacts than its ethereal forces. When creating normal artifacts of any sort, halve the costs in essence for a Smith.
Allowing any of its artifacts to be destroyed, or losing an actual artifact, causes a Smith to lose essence equal to its forces.
With a successful intelligence check, the Phantom becomes incorporeal for check digit minutes. Treat this like a celestial form for all purposes, including creating disturbance. With a successful precision check, the Phantom may avoid detection. Anyone actively searching for the Phantom may make a perception check at a penalty equal to the phantom's check digit.
Being forced to reveal information or secrets causes a Phantom to lose essence equal to its forces.
The Favored may spend essence retroactively after making a d666 roll. A number of times per day equal to its ethereal forces, the Favored may make a precision check after making a d666 roll. If successful, the Favored's player may reroll one die in the original roll, either normal or check digit; he must accept the new result. The Favored may state some desired immediate goal and make an intelligence check; if successful, the GM will give a suggestion as to how this could be accomplished in the current situation, setting up coincidences as necessary. Check digits of one provide only simple opportunities, while check digits of six can reveal complex Rube Goldbergesque machinations.
Failing ANY roll with a check digit of six causes a Favored to lose one essence.
Before any perception-based check, the Investigator may make an intelligence check and add the check digit of a successful roll to its perception. The Investigator's player may attempt a precision check to obtain a gut feeling about what might be a good idea to try next; failure means he cannot try again for check digit hours.
Failing a modified roll with a high check digit, failing to uncover useful evidence that the Investigator could have obtained, or failing to come to an obvious conclusion causes it to lose essence equal to its forces.
The Charmer adds its Ethereal forces to all its social rolls.
Having someone take a severe dislike to the Charmer causes it to lose essence equal to its forces.
The Horde may have multiple vessels manifested at once, so long as the total forces of its vessels (as per the force-equivalence of vessels given in The Marches and Heaven and Hell) does not exceed its total forces.
Being forced down a single path of action, or being unable to make any choices causes the Horde to lose essence equal to its forces.
Note that most of the above rules have not been extensively playtested. Actual costs, penalties, and bonuses may require some tweaking to feel balanced.
A high check digit tentatively means a check digit of [7 minus the check digit of the boosting roll], or higher. This may be too harsh, and might need to be amended to simply mean a check digit of 6.