I've done this once, a couple of years ago. I think I converted a 3.2K to 3.2U using a package from some gentlemen in China. It was a long, arduous process, but after a lot of nailbiting I eventually emerged with a fully converted, U.S. English Wii.
Now I have a new one with 4.3K on it. Can this still be done? Should I bother researching more into this?