The entire package is actually made up of a number of different pieces, of which I only created two small bits. The pieces that I wrote are hld2mtex, a script for converting a source file into musixtex format, and neumes.mf, which defines a font to use for Hildegard's neumes. The other packages that you need are TeX, MusiXTeX, and Perl. All of these packages are platform-independent, and so should run on any computer.
Here are more detailed descriptions that should explain everything completely:
If you have any comments, suggestions, requests, or bug reports, feel free to email me at ali@blindchicken.com.