It seems that one of the more enigmatic C-41 steps is that of "stabilizer." That was the name given to older color processes for the final stage to, well, stabilize the dyes from environmental degradation. According to PE, IIRC, what we still call stabilizer now is more on the order of "a chemical to hopefully prevent little organic nasties from degrading the dyes sometime in the future." The chemical of choice across all of the homebrew kits that I've examined by MSDS is Hexamine.

Hexamine is a derivative of the old stabilizer formaldehyde after reaction with ammonia. (Which makes me sort of wonder if there still isn't a dye stabilizer function going on.) Unlike formaldehyde, which is highly toxic and not fun to ship, hexamine is actually used orally for medical puposes and is a solid.

When I used to do backpacking and general knocking around, I used one of those Esbit solid fueled stoves. http://en.wikipedia.org/wiki/Esbit The fuel tablets are 80-90% hexamine, and the other binder is a related formaldehyde/ammonia compound! These tablets are available from many sources online and are very cheap.

How much to use? My Unicolor K-2 powder kit uses 9.98 grams for a 2 liter batch. So, say, 5 grams/liter. It is soluble in water at 20 times that.

I did not link all of my resources for ease of reading. If anyone can show that I'm way off base, please do so.