Forrest --
Yikes, sorry 'bout that! We retired the old "makegen" code quite awhile ago. I didn't realize there were still links to it that people were using! RTcmix is still very much alive and well, known-to-but-a-few. :-) It's morphed into a library that is presently embedded for use inside OpenFrameworks, iOS, Max/MSP, Unity (been working with it in Unity for about 1.5 years, it's *really* fun!), and of course still standalone.
We moved to a completely new server system in the Music Department here at Columbia, and it looks like the older RTcmix documentation got blitzed in the process. I have a copy of it all and can put it back on-line if people are clamoring for it.
In the meantime, CSOUND still uses this older system (CSOUND and RTcmix/cmix share a common ancestor), and this may answer your questions about how the GEN routines work:
brad