I highly doubt it, though, for a good reason. GameCube's C button is an analog stick, while N64 had a controller with 4 C buttons, one for each direction. In many games it can make a big difference which one you press (i.e., in SM64, pressing C-down zooms out, while C-left rotates the camera). There may even be N64 games which require you to do certain things by holding two opposite C buttons, like C-left and C-right! I think it is technically possible, though the hassle probably wouldn't be worth it.