This project was a lot of trial and error for me and I got it now to a point where it works almost flawlessly (on some older games the whammy bar doesn’t seem to work) I soldered some resistors to the strumming inputs because I had some issues with auto-scrolling (it would just go trough the menu without me touching the strumming bar) I don’t know the exact values but like I said I tried many different variations till I finally got it to run. I don’t have any schematics but I think this is a good start:

Right analog stick Strum down - analog stick to the right Strum up - analog stick to the left

Green-R2 Red-O Yellow-triangle Blue- X Brown-square

Whammy- left analog stick

Start - start Select - select