I described the motivations and the basic workings of the system in my article "On musical typesetting: Sonata for TeX and METAFONT, Op. 2," published in TUGboat 24/2 (2003).
The on-going development of the program has been documented in (so far) three 'log files,' in which I described algorithms, strategies, problems, and decisions. The first one was written in Spanish, but I changed to English from the second one on, because, after all, I was programming in English, so it was more natural.
The "TeX Development Fund" gave me a grant for the 'first stage' of TeXmuse in the summer of 2005. The `first stage' was defined as a program that typesets Bach's Inventions, and I submitted it to CTAN on August 31, 2005. That package is up here too, below.
But I decided to keep the first thing I put up in this, the official webpage of TeXmuse. It contains the version of the program as of July 1st., 2005, two samples, and the three logs as they stood then. It is all now in the file 'texmuse july 1-2005.zip.'
The current state of TeXmuse is here:
firstpass, secondpass, and inventions.
texmuse.tex, texmuse.mf, and txmfont.mf.
.tex), and an auxiliar class required to typeset some of them, are in sampleinputs.zip.
mainloop.pdf), an installation and running guide (running.pdf), and a list of shortcomings and wants (wants.pdf).
As part of the commitments for the grant, I am writing a second article for TUGboat, documenting the process of completing a the first stage of TeXmuse.