Unfortunately Guitar Hero III on the Wii system does not support downloadable content as with the PS3/Xbox360.
RedOctane (publisher) cites lack of space as the main reason.
you can download songs online and insert it to your guitar hero game. search how to download songs to guitar hero two.
You can't download songs.
no.. not at this time
No
you cant
nope
No
Illegally, yes
You can't.
No. How do you expect Guitar Hero to make any money off of download-able songs if people can just play their own?
No, Guitar Hero 3 has no DLC, if you wanted to put new songs on it you'd have to hack it somehow. The new Guitar Hero: World Tour will have DLC though, you'll be able to download songs onto and play songs from your SD cards (they will probably let you download all the songs from the previous games). If you want more info on Guitar Hero: World Tour for Wii check out the Related Linksbelow.
No, you can't. :(