Highly unlikely. The guitar part in the game is not a simple transcription of what the lead guitar plays, but an amalgamation of all of the guitar parts in the song. When you have things with 2 guitar parts, the guitar track isn't just 1 of the 2 guitar parts, but a mixture of both.
Look at Hangar 18. Two guitar players trading solos back and forth, but in RB, it's all compressed onto a single guitar track.
Your best bet would be if sometime down the line RBN added pro guitar support, because then maybe someone might do something along the lines of the Rodrigo y Gabriela tracks with pro support, where the "bass" part is just a second guitar part. I wouldn't hold my breath on seeing that in official DLC, though.