[James]

I think for the US SNES, there's just a plastic tab inside the system that prevents Japanese catridges from fitting in correctly. So if you just break it off, you can play the games just fine.

Installing a translation to a catridge, though, is really not an option. I do think there are SNES emulators that have online support, so you could just play a patched version of the game over the internet with him, though don't ask me how.