you can try commandeerMii.
http://forum.wiibrew...ad.php?12,63968
but since it is relatively untested, i would suggest you make a backup of your wii before you run it in case it borks all your miis.
there is also a side effect that if have a mii on your wii that was created on a different wii, and you start playing a game with that mii (like wii sports). when you change that mii to appear like it was created on your wii, it usually will break that save.