From 2007 - 2011, I was one of a team of 3 developers working on Wii64, among other projects. I’m really proud of the work we did porting Mupen64 to the Gamecube & Wii platforms - which are really resource strapped.
You can dig through the archives of EmulateMii to read more about the project. Or find the source code on GitHub. The project still lives on through the Not64 fork!