No I mean to play those in Blitz.
I just bought my first Xbox and RB1 used for the export (because the other discs are getting near impossible to find new in stores now... will have to keep hunting). I haven't picked up RB3 yet, but I did get Blitz. To export the songs in RB1, no code was required, all I had to do was pop in the disc and choose "Export Songs" from the game's menu. Black Hole Sun and Dani California show up fine in Blitz, even though I don't have RB3 or the patch that restores those songs to the game.
Weird. I exported my Rb1 songs into RB2 years ago.
Do I need to do this again?