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).

>>5
In the original source code of a ROM, you'd have an entire directory structure that has sections for art, music, control code, additional code, etc. that makes it easy to expand on. When you assemble this file, you'd link all of the other files together to get the final ROM. (No one puts all their code into a single file. You'd be dealing with a 30 MB ASM file that assembles into a 3 MB binary ROM. Can you imagine editing that? That's why I am curious about doing a split disassembly instead of just hex editing or making an IDA database.)

A split disassembly, as I understand it, is when you disassemble a ROM and split it up into what is more or less a recreation of the original files.