Coming in here a bit late, I'm pretty much thinking out loud, and it's probably a stupid question, but would it be possible to use C-41 or E-6 type couplers, in solution with one of the CD's, as a second developer on standard, reverse exposed B/W film? Or do those families of couplers have to be adsorbed to the silver halide crystals to work? (So what I'm envisioning is sort of a split K-xx process, where the couplers and developer are in the same solution, using two -- or three -- separately exposed standard b/w films, which would then be sandwiched.)

I think PE has said you could do this with the Kodachrome couplers, but since those aren't readily available, that's not a viable solution.