Well, I don't know anything about PIC programming. So, to tell you the truth, I have no idea why I'm browsing around this forum. :lol:
Anyway, I have another idea that might work. If you buy a cheap, plug&play keyboard, and gut the circuitry, (But not the BOARD, meaning the part that all of the key press against) than you could simply wire all of your buttons from your controller to where the keys from your key board WOULD be if you didn't remove it. Now, come to think of it, that would be a HUGE pain because you would have to solder ALL of the NES controllers' buttons separately. So... let me know what you think. It might be a pain, but if you think about it there are only 8 buttons including the D-pad. And if you come up with a better idea, let me know, 'cause this one is going to be hard. :?