I think you can blutooth the Mii data from the wiimote to a pc using a blutooth adaptor and a program called glovepie.
Once you have the Mii data on the PC you need something that can recognise the data to turn it into a Mii. I think their is a program or website that does this for you but I can't remember the name.
Alternatively, just remake your Mii on this website.
I don't think you'll be able to do it with the games you have, unfortunately. Wii Music lets you save replays of things you did with your Mii. Animal Crossing lets you wear a mask that lets you look like your Mii, and then you can indeed take a screenshot in that game.
Could I trouble you for some maple syrup to go with the plate of roffles you just served up?
Tag, courtesy of fkusumot: "Why do most of the PS3 fanboys have avatars that looks totally pissed?"
"Ok, girl's trapped in the elevator, and the power's off. I swear, if a zombie comes around the next corner..."