You can get the current release at cl-menusystem-2003-09-19.tar.gz. The documentation might not be too illuminating on its own, so reading the test case should help tremendously.
You can see a slightly out of date test case here, which is the best I could do for "screenshots" of a currently text-based program.
This source was placed into the public domain by Brian Mastenbrook.
It also has a page on CLiki.