I think so, if you really want to destroy a Game Cube controller. I think there are no restrictions on where you get your buttons and switches from, other then it has to plug into that 15-pin standard joystick port.
I would take out all of the electronics in there except for the buttons, get an old 15-pin cable and cut off one end connector, and replace the original Game Cube connector with it so you can wire it up nicely.
Happy desoldering
