GCBooter is a simple application which allows anyone to boot their original GC games from Wii mode. It is region free and works from the homebrew channel.
This is far simpler to use than having to patch your system menu for region free :)
Just copy the GCBooter folder into your /apps/ folder on your card and run it via the homebrew channel. Onscreen instructions are self-explanatory.
Wii (with the ability to boot some Wii homebrew) Gamecube Game Gamecube Controller
GCBooter is based on Bushing's code at http://forum.wiibrew.org/read.php?8,925
Thanks to shagkur for libOGC :)