Rafael Mizrahi has put some serious work into this Guitar Hero Robot called Guitar Heronoid. If you are not very good at Guitar Hero this robot may be what you need to get some high scores. If this hack it a bit to hard, why not go wireless first.

“The robot is divided into two basic parts, “brain” and “body”.
The “brain” is in charge of detecting and analyzing the PS2 video signals.
The “brain” generates play-commands (which tone to press, when to do it and when to strum) for the “body”.
The “body” reads the play-commands and controls the fingers movement by them.”