Originally Posted By R. Belmont
...and probably some extreme cart remapping in MESS...


FWIW, the following code should cover the cart ROM remapping part.

Code:
while (read_blocks < 64 && read_blocks < total_blocks)
{
	/* Loading and mirroring data */
	memcpy(&snes_ram[0x008000 + read_blocks * 0x10000], &ROM[0x000000 + read_blocks * 0x8000], 0x8000);
	memcpy(&snes_ram[0x808000 + read_blocks * 0x10000], &ROM[0x000000 + read_blocks * 0x8000], 0x8000);
	memcpy(&snes_ram[0xc00000 + read_blocks * 0x10000], &ROM[0x000000 + read_blocks * 0x10000], 0x10000);
	read_blocks++;
}


Not sure about the changes needed for the SRAM.