For MP3 (and most other games that ignore lefties), I just hold the wii mote in my left hand anyways. It's fine that way most of the time.
There are some games that are ok most of the time, and then they throw in some sort of rythm part where you have to waggle a certain control at a certain time and having them swapped can really mix you up, but I don't recall that problem with MP3.








