@arcadelover15 There wasn't a whole lot to it. The box itself is designed to be used as a controller if you want, so it was just a matter of hooking up BOTH usb cables to the Pi. (Each cable is one side of the control panel.) I think the setup tweak I used initially might be no longer needed in current versions of RetroPi.

Here is a thread I gave my info in:
https://retropie.org.uk/forum/topic/30623/pandora-box-used-as-game-pad