Uploaded a work in progress version to show what I've been doing.

For now:
-It resets properly on the Wii (still not able to return to the loader, though.)
-Reads files from the front Wii SD slot (saving disabled, forgot to reenable it before uploading, but you can remove the return lines on SYS_FileOpenWrite and SYS_FileWrite to make it work.)
-Wiimote suport, tried to map the buttons on the wiimote and nunchuk more or less like the gamecube ones, wiimote IR aiming and nunchuk up-motion jumping.

Bugs:
-Wiimote disconnects too fast, need to read the libogc headers again and determine how to make the idle time longer.
-If the wiimote disconnects, screen turns grey (only the game screen, not the status bar or menu) and stays this way until you reload the game (starting a new game won't help)
-Maybe you'll have to disconnect and reconnect the nunchuk to your wiimote to make it work (again, this is a 1-day, no-prior-experience implementation, it will be fixed)
-Something else I can't remember.

That's it, please don't complain about the wiimote implementation and SD card reading yet. The wiimote code is completely new to me (and I don't know about the real stability of the code on the libogc cvs) and the SD reading doesn't use libfat yet, but use the wiisd functions from the latest libogc CVS.