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
Usage

Just copy the GCBooter folder into your /apps/ folder on your card and run it via the homebrew channel. Insert your GameCube disc and press A on the GameCube controller a few times.

Link