I just tried switched the region mod fix, outlined here:
http://www.raveware.co.uk/Files/gcmod.pdf

The instructions are for modding a Japanese GC to play NA games. The method to do this to mod a US GC to play japanese is exactly the same as the instructions here, except, you are switching jumper R5, instead of jumper R6. No traces need to be cut.

Warning! Better get it on right the first time. The solder points are SMALL, I mean SMALL! This is the finest solder point I have ver attempted. It would be very easy to lift the factory solder right off the jumper, leaving nothing for the switch to connect to, eliminating the possibility of ever doing the region mod.

Otherwise, it's great. Get a super tiny switch (SPST is fine), and you can mount it right on the inside of one of the air vents directly under the Digital AV out jack.

That is all. You may go back to your regularly scheduled threads.