Split disassembly programs?

Alternatively titled: Good splitting programs/how to write a splitter?

I've done some disassembly before, but never a split disassembly. Are there any good programs that will find the pointers for me and split a ROM, or do you have any tips for writing a splitter?

Target machine is a Sega Mega Drive/Genesis (MC68K and Z80).

>16
Actually, Sega are bros. See Sonic Retro's work and Sega's treatment of them.