Some thoughts...
So despite the lack of posts, this project is moving ahead.
Dye-imbition
I'm in the process of getting a hold of suitable dyes to use. There are many appropriate acid dyes out there, but their availability is another question. I've bought some WashFast Acid textiles dye, magenta, and it appears to be a reasonable magenta; though I have no way of knowing yet. Anyways, the key is to get a matrix, a.k.a. an unpigmented carbon tissue on a reliable support (fixed out lith film for instance). This process resembles the pinatype process, which is just like carbon printing, except there is no hot water etch and no pigment in the glop. After exposure and a wash, there are two types of gelatin, unhardened and hardened. Then, you soak the dyes in a mild acetic acid solution with the matrix, the dye will imbibe in the matrix in the unhardened area (thus, you need a positive to contact print). The matrix is then rolled onto a paper support (fixed out b&w paper should be suitable for testing, a mordant of copper sulfate or whatever the dye-transfer folks use should be suitable) and left to transfer its dye to the paper. Once a set of dyes are found, this process should be quite doable for anyone who can make a decent carbon tissue. JS Friedman lists a number of textile dyes that are suitable; so it can be done with fabric dyes, in theory at least. They are cheap and a little goes a long way.
Color Carbon
I've been thinking less about this lately, but it's an equally exciting process for amazing and completely archival color photographs. The proper pigments are yet to be determined (by me at least). The key is 3 transparent pigments; and contrary to what I stated above, just printing the most opaque on the bottom isn't necessarily going to work, as it must be transparent enough to show the white paper through so you get some kind of continuous tone. People over at the Bostick & Sullivan Carbon forum have some experience in this and would be a good resource.
But to me, these processes solidify color analog prints far into the future, after all Cibachrome and RA-4 papers are discontinued (god forbid). The materials are cheap, readily available and nothing is necessarily "photography" specific. Gelatin, paper, potassium dichromate, pigments, etc.
Anyways, here's what I see as the necessary steps to making these processes viable:
For carbon prints... pigments and a reliable registration method. That's it. If some carbon printer out there wants to start testing different pigents/inks in monochrome, as soon as you can make a reasonable print in each color that is continuous in tone, then all you have to do is layer the 3.
For dye-imbition... suitable dyes. Duh. More specifics to follow, but a dye that will imbibe into a matrix in a solution of diluted acetic acid, and then transfer to a paper.
Another modification would be a carbon method where the gelatin layers are dyed as opposed to impregnanted with pigment. Then, you could theoretically use the same dyes for a carbon print and a dye-transfer print. The questions would be how to mordant (make stick) the dyes to the gelatin, but if you make gelatin with food dyes and let it dry, the dye doesn't go anywhere, as I've tested. So it doesn't seem like it'd be that hard to just make dyed gelatin tissues. Something to think about.
BREAK!