Can you import rock band 2 song onto RB3 on the Wii?

For old DLC, (stuff you bought from the rock band 2 store) you just have to have the SD card with the data in the wii when the game starts. It will see that the songs are there and (the first time only) take a few minutes to add the songs to your library or somesuch, so that they appear in the track list.
For importing your Rock Band 2 on-disc songs, you will need to have a save file from the game on your wii memory, and the option to do the import will show up under Redeem Code -> Previously redeemed codes, where you then pay your 1000 wii points and it downloads the songs.
Finally, for Green Day, you go to redeem code, put the code from the back of your green day manual in, and then proceed as with the rock band 2 stuff (previously redeemed codes, 1000 wii points, huge download.