I'll see what I can do about writing some code for this. I believe there are issues reading the ccbill cookie due to browser security. It would likely be easier to just set a separate cookie under your domain that is read. Your site would then look for the cookie and act appropriately.
Quick Example:
User sent from ccbill link:
1. User hits ccbill landing page.
2. Special cookie is set with expiration equal to the ccbill cookie under your domain.
3. Proceed normally to ccbill signup
Type-in:
1. Render main page as normal.
2. If join link is clicked, attempt to locate cookie and read it.
a. If no valid cookie, do not set and proceed as normal (e.g. Zombaio).
b. If valid cookie set proceed to ccbill signup form/cascade (so affiliate gets credit)
This should work rather well I'm thinking. It would just need to be written.
Note: we could make it more complex to handle multiple affiliate backends too. Such as if you had verotel, ccbill, and zombaio affiliate programs so that the affiliate always gets credit for their typeins.