I don't know if anyone else noticed but there was no Wii library in Arduinos library manager, just a bunch of half broken sample code scattered around the internet. I pulled all the projects together into one project, cleaned it up, made it a bit more modular, and added a function mapping feature. Then I published it into the official Arduino libraries. You can find it by searching your library manager for Wii.
Anyone interested in collaborating, send pull requests and issues to: GitHub - madhephaestus/WiiChuck: A library to provide Wii accessory access to arduino devices Via Wire.