ABOUT IOS37+, AND HOW NINTENDO MAY BLOCK CUSTOM CHANNELS IN FUTURE
Channels are provided in WAD format, and are currently installed using Waninkoko's WAD installer. This puts a trucha signed channel onto your Wii system, and assigns it a fake ticket to fool the Wii into accepting it. "Trucha signing" is also the method that Datel use in Freeloader.
You may have heard of something called IOS37. If your Wii is fully up to date (as of the time I wrote this introduction - May 05 2008), then your Wii already has "Starlet" firmware IOS37 waiting to be used in its update partition. When Nintendo update the Wii System Menu to use IOS37 (or release a game/channel that requires it), it is widely believed that all trucha signed applications will no longer work. The good thing about such updates though is that they require a prompt, and warn the user before updating. Until the next update, your console can happily install WAD files / Homebrew Channels. I recommend you check this thread periodically for updates on IOS37 and future IOS firmwares, so that you are constantly aware of what effects they may have on you.