If you're looking to do a LxTHW, you should contact Zed to get the latest base structure.
Edit: Also, if you want to write a Learn X The Hard Way you should read this post about how to do it (http://sheddingbikes.com/posts/1288945508.html)
My goal was, if I could write about code and music at the same time, then making a build system for books would be easy. The above is the end result of that work. Enjoy.
I understand you don't want to use LilyPond because it is too complex, but you may want to know that LilyPond comes with a tool to convert from ABC to LilyPond (abc2ly). One could use it to write the music examples in ABC and have LilyPond typeset them. I'd consider using a setup like this to typeset the "final" version since LilyPond's typography is so nice.