The feature that maps the Wii remote input to a GameCube controller is amazing, and I think it would be awesome if the same can be done using a Wii classic controller.
I'm pretty sure you mean the GameCube controller input to the WiiMote controls? If so, Aurelio has said that it is one of his goals to add classic controller support, he just hasn't got around to doing it yet. If you do mean Wii remote input to GameCube controller, I have no clue what you're talking about.
I seem to remember there being a function in either RVLoader or Nintendont that allows you to bind GameCube controller controls to a Wii Remote and Nunchuck. It is effectively the inverse of GC2Wiimote. I don't remember where exactly I found it, but I thought it was worth mentioning here in case that's relevant at all. If you want I can do some digging to see if I can find exactly what setting I'm talking about.
I'm pretty sure you mean the GameCube controller input to the WiiMote controls? If so, Aurelio has said that it is one of his goals to add classic controller support, he just hasn't got around to doing it yet. If you do mean Wii remote input to GameCube controller, I have no clue what you're talking about.