OK so i've recently encountered nintendo 64 emulators for my computer. because of the way the controller is set up, not all of the games/functions are entirely compatible with the keyboard. this gave me the bright idea that maybe i could mod a controller for the console to plug it into the USB and use it like a normal computer joystick/controller thingy.

any advice/input would be appreciated.
See above post ^
can you not buy a controller to usb adapter? im sure you can for playstation controllers, and the same with using xbox controllers on your playstation. so i assume theres some for n64 - pc
Not only would you have to completely and correctly rewire the controller to actually be USB compatible, you'd have to write your own drivers to make the controller even be recognized, let alone work.
i think they make n64-style controllers for USB, or at least they used to. look them up on ebay.
you can get USB ones I'm sure

"Save The Cheerleader, Save The World"
- Hiro Nakamura
A friend of mine used his PC game controller which looked identical to a Playstation controller to play N64 roms on his laptop. It was a little weird to adjust to, but other than that, it worked fine.