Taken directly from the article on hackmii:
Open-Source Apploader, ISO template
August 2nd, 2008 by bushing · No Comments
In order to make legally re-distributable ISO images for the Homebrew Channel installer, we had to remove Nintendo’s copyrighted apploader code and replace it with our own; we based ours on the one from GC-Linux. You may find the source and binary for it here:
Here is an empty “template” disc image that you can use in your own projects; it contains the above apploader.