Going directly to the source

I'm spending the morning reading the MAME Canon Cat "driver" sourcecode to see if I can figure out how to use it. Simply running it, I can't figure out where essential things like the LEAP keys are. The code is well commented, which is fortunate because my C++ is rusty, and I don't even know how to configure MAME let alone write drivers for it. As I read through the code I feel like I'm starting…