It's really easy to do, it's not illegal since they don't use any nintendo code for the homebrew channel, then you have to question the leagality of every piece of software you run through it.
Emulators would not be illegal but ROM images are... Homebrew games programmed for it would not be illegal either, media players are legal too, (but the media you run might not be).
One great piece of software that you should run is ScummVM, software is legal and it lets you run your old point and click adventure games from your wii, with wiimote functionality. ;)







