Personally I would use the touchpad as the C-pad by dividing it into four quadrants (like I did for the Xperia Play port of my emulator). This is superior to using the analog stick, because it avoids the problem of hitting diagonals resulting in unintentional 2 button presses, and makes it so opposites can be pressed simultaneously (not that that was ever needed for any N64 games AFAIK - maybe for combo codes or something but certainly rare). That said, the OUYA does have a USB port so N64 and other controllers can be easily adapted to USB and connected to the OUYA, and bluetooth is also an option. I'm also personally working on a project to hack a N64 controller so that it appears to be a native OUYA controller to the console. If I'm successful, I'll also post the specs for that so others can copy it.