I have been working on a set of detailed instructions for setting up a development environment for the Gamecube and Wii. One of the main goals I have for this is to be able to compile each library from its source, rather than just extracting an archive full of prebuilt libraries. This will protect the libraries from possible extinction should the original people who port them to the GC/Wii stop. As well, should newer versions of the original library (like libpng for example) become available, it will then be quite easy for anybody to be able to build them again.
You can view the work in-progress via Google Docs. There are instructions for both Linux and Windows. Give it a walk through and let me know if it works for you, or if there are other libraries you can think should be included. It isn't complete yet, but I hope to have it ready to compile the more popular apps (like the various emulators) soon.