For the following steps, don't type "quotation marks". The steps should make sense with what you have on your screen.
1. download
ModMii
2. extract it on your computer
3. run modmii (modmii launcher)
4. type "I Agree"
5. press [Enter]
6. let it check for updates
7. type "1" and press [Enter]
8. type "BC" and press [Enter]
** step 8 1/2. If you don't already have a WAD manager on your Wii, at this point press "2", [Enter], "YAWM", [Enter].
9. type "D" and press [Enter]
10. type "Y" and press [Enter].
11. wait for it to download.
12. type the letter "O" and press [Enter]
13. put the SD card from your wii in your your computer.
14. Highlight everything.
15. right click, point to "send to >" and click on your SD card drive.
16. put the SD card back in the wii and install the WAD file with a WAD manager.
I don't know why I found typing that up so much fun ... oh well. Edit: maybe that's why I like programming so much.