Quoted from PinballMikeD:
I've often thought about putting a PROC in my machine and playing around with the rule set. I wouldn't change the music or DMD animations, just tweak the code. That's why I'm interested to see what people think could be improved.
Just remember that if you put a P-ROC in, you have nothing. If you want the original game back, you have to write it from scratch. It's not like reverse engineering something where you're making small changes to something that exists; you have to write everything you want it to do.
Not that I would discourage that kind of effort, I had a blast doing CCC.