Are 32X carts completely pin-compatible to genesis carts? how do they identify as 32X carts, I assume by having a grounded pin (similar to the way the SMS adapter works for setting the genesis to SMS mode), if so, which one?
Well, doesn't it work to plug a Genesis cart into the 32X cart slot and have it run normally? If so, then I bet the pinout is identical, at least for RAM/ROM access. I think 32X games are identified by having a different system signature in the cartridge header, something like SEGA GENESIS 32X rather than SEGA MEGA DRIVE or SEGA GENESIS. The 32X BIOS probably detects this and boots the cartridge differently.
I actually had someone send me some genesis bootlegs from brazil, and replaced the eproms with sockets, plus rewired them to work for up to 32 mbit (ex-cyber helped me quite a bit with the latter).
if you can get any of those carts, look for the ones that use 4 eproms for the game.. those can be configured for up to 32 mbit, using 27c8001/27c080/27c801 eproms (or 4001/040 for up to 16 mbit).
they'll work without modification for 32x games too.
something similar applies for SMS too, btw.. you can use a monopoly cart to convert it to use a 4001 eprom, including sram (phantasy star, baby!).. mike G sent me the info on rewiring those, and it works great.
you need an eprom burner of course, and some tools Eidolon wrote to convert a .bin genny rom to the right format.. you have to dump the original game eproms first to find out how the rom parts are ordered, then use eidolon's tool to split a rom properly, and burn the parts in the same order as the original rom from the old eproms.