As far as I know, no one intends to sell commercial CMYK tissue. I suggest you familiarize yourself with the process of making traditional black carbon tissue as discussed on this forum and on the Bostick & Sullivan forum.
Then fully read through this thread and one entitled "Diazo-Sensitized Carbon Transfer" (http://www.apug.org/forums/forum42/9...-transfer.html)
More importantly, IMO, it will help if you go through the process of making traditional dichromate carbon prints first. It will help you understand where the process for making and using pre-sensitized tissues differs
The next step is understanding color separation and multiple-register printing.