I would also like to know how to do the multicolor led mod for US/japanese games.
If you do an IC mod switch, you just use a DPDT switch instead of a SPDT. On the second switch circuit, run 5V to the center pole, and run each switch pole to a different LED (with appropriate resistors) That way when the switch is one direction, one LED illuminates, and the other way the other LED illuminates. Really pretty simple honestly
I may do this to my Duo-R when I finally region mod it.