I've been frustrated by the inability to use GameCube controllers for Dolphin on my Mac over this "unsigned driver" issue. When I saw the new Gbros. Bluetooth Adapter, I decided to give it a try even though the vendor only listed Windows support. I'm glad to say it works great!! I had to map everything, bit it works great! Finally, Mac users have an easy way to play Dolphin with a real GameCube controller! Rocking out to Metroid Prime tonight!!
http://www.8bitdo.com/gbros/
http://www.8bitdo.com/gbros/