My original goal was to create a machine that looked 100% original but would play a ton of games that have the ability to work with only a single button. However, this left out Sinistar

! I really don't want to start adding buttons because I know that I would eventually add more and more to my control panel.
This goes against the whole idea of keeping the ROMS original, but...Would it be possible to alter my ROM so that the Player2 button would function as the Sinibomb button? It seems like it would be fairly easy if it is possible...can anyone out there do this??? Help!