It shouldn't be much harder than making an NES cart, I think. SNES uses 8-bit ROMs, so it's uses pretty much the same chips as NES.

But you'll need a cart that exactly fits the specifications for the DW games. Such as if it's HiROM or LoROM, SRAM size/battery (larger SRAM than needed might be OK), and the ROM size (some boards take multiple smaller ROMs for large games, I think). Plus if it's FastROM, you'll need to use ROMs that are rated to a certain access speed (I'm not sure what exactly).