Step 1: Symphony of Destruction
First open the guitar and cut the controller wire off the board.
Then cut the traces to all the switches. (Fret buttons, Strum Switch, Start/Select)
Next open the SIXAXIS and cut the body so that the flat part where the start and select buttons are.
Last cut the guitar body where you want to put the controller.
I positioned it so I can charge and see the controller number above the strap.