It is, but AFAIK only if you hardmod it. I have a Wiikey 2 in mine and it works fine. Just find some modchip that has D2C and GC game support and you should be fine. If it's softmodded anyway though, what's the problem with replacing the MIOS? cMIOS or Dios Mios both work great (although I can't get Rayman 3 to work with Dios Mios installed).