I know I've seen examples of people doing this, but I can't find them. I would think it would be fairly easy.
You could just hack the controls and power into an old serial, parellel, or vga cables. Then you could use a switch-box designed for that purpose. I don't remember how much power the plug-n-plays use, but I would think that it would be low enough to use the cable's wiring.
Another option would be to have a switch to control which one gets power from the wall wart.
I would think you could just wire both systems into the controls at the same time. It's not the best way to do it, but it should work fine. It probably wouldn't be a bad idea to run seperate grounds and have a switch to control which one was active for the controls.