Hey, kind of you to ask before doing it !
If you credit the original code back, it's fine :-)
(You could also make a PR in the original project by the way)
I'm curious to see how it goes ; is there any chance you can ping me when you have a demo?
Game has been updated to 0.10.0 with the A+B buttons enabled for the second player ;-)
Of course, should be pretty easy to implement. Will update asap :)