You can build the workdbook from source code on all major operating systems. You will need to install Lilypond and LaTeX. You can get LaTeX easiest by installing the texlive packages from your distribution's repository. On Windows I recommend MikTex.
Besides the base texlive package, the following LaTeX packages are used in the workbook:
To use the Makefile (highly recommended) you also need to have GNU Make, which is normally already installed on all Linux systems as well as on Mac OSX. The Makefile will not work on Windows, though, so special Windows instructions are given below.
To build on Mac, be sure to configure your system according to the instructions in Lilypond's Application Usage manual, setup for Mac OSX. Pay particular attention to the Python setup, and be sure to use Python 2.6, as Python 3.0 doesn't work right. You need to put the right Python PATH at the top of the lilypond-book python script. Here's how it looks on mine:
#!/Library/Frameworks/Python.framework/Versions/2.6/bin/python
The preview command depends on Acrobat Reader, but you can substitute your pdf viewer of choice in the Makefile if desired. Just change "acroread" to "xpdf" or "evince" or whatever (or simply comment it out of the Makefile).
To build the workbook, type "make pdf" from the top directory. The final pdf file resides in the "out" directory with the name "workbook_main.pdf".
The command "make keep" will build the workbook and put a copy of it named "GratisAdParnassum.pdf" in the top directory.
"make clean" removes all incidental files (and also the pdf if you haven't run "make keep" yet).
It's possible to make an html version from the same source files by running "make web" from the top directory. The quality isn't as nice as the pdf version. This function depends on the latex2html package, which should be available in most linux distro repositories.
After installing MikTex, use the MikTex package manager to install the "ms" package from the repository. If it has trouble getting the package, choose "Repository>Synchronize" and then try again to add the package after the repo has synced up.
For Windows users I've provided a batch file build.bat with the commands necessary to build the workbook using Lilypond and LaTeX, and you can either simply double-click the batch file or you can find the FreeCounterpoint directory at the DOS prompt and run it from there by typing "build.bat" and hitting "enter."
Of course you would be foolhardy not to view the contents of the batch file first, so I encourage you to right-click the build.bat icon and choose "edit" from the menu so you can see what's in there.
After building is complete, the .pdf file of the workbook is in the top directory with the name "GratisAdParnassum.pdf".