Just use the Rebooter option in Neogamma. Set the rebooter option to skip update and copyright check. Then click use rebooter, and your Wii will restart. Click on the Wii disc channel, and Guitar Hero 5 will actually load there.
I've tested this and it works great.
Always use the newest Neogamma for best compatibility also.
http://www.gbatemp.net/index.php?showtopic=175361
(Yes I'm aware this is an old ass thread, but It shows up on front page google search's. So thought it would be best to leave the solution.)