Assign input device to out of focus program

Hi,

I have a weird sort of question.

I want to know if I can assign a usb gamepad to an out of focus
program.

What I am trying to do is have a nintendo emulator on once screen
while I use another program on another screen. I want any input from
the gamepad to go straight to the nintendo emulator, but my keyboard
to go to whatever other program is in focus.
Basically my wife wants to play some nintendo games while I use the
computer, and we only have 1 computer. Is this possible?

Thanks,

-Joel