In theory this is possible because all you really need to do is carry the control signal wires and a common ground. If you plan to use audio or video features from your supergun then that gets even more specific to the application at hand but for this kind of setup I don't think you would be running video and audio to your super gun.
Power wise, yes you need to power the IO board using the P1 header, this is how these boards get powered in vewlix cabs.
But you can certainly take a Jamma edge connector and manually build an adapter harness for the controls using the 60 pin IDC/MIL connector "G".
Just make sure you double check your work and check it with a multi meter on continuity if you have to.
Also at this point, if you are making custom harness's, if you really wanted to, you could even shove the IO board in a fight stick and manually wire the controls from the G connector to the buttons haha.