Change the BIOS chip. It's socketed and on the bottom board so you'll have to take the stack apart to get to it.
You can replace it with a US BIOS or with a UniBIOS. For home use the UniBIOS is really slick - you can enable cheats, God mode, play the cart music in jukebox mode, etc...
I can program you a BIOS chip. It's a service I offer through my website, but I can't do the UniBIOS chips that way. My agreement with Razoola is that I do them as an installer only.
RJ