Most of the methods out there are out of date including the ones on this forum.. I recently rehacked my Wii cause I wanted everything to be up to date as possible so I did a little research since it's been a long ass time since I did anything with the Wii.

By far ModMii is the best method, and can modify ANY WII. 
You can get it here: http://modmii.zzl.org/

You simply run the program on your PC and answer a few questions about your Wii and the program will generate all files you need and a simple to understand guide to fallow.

ModMii installer can be found here http://turdinc.kicks-ass.net/Msntv/ps2/downloads.html