Although I tried searching and looking at your former posts, I couldn't find your "quick rundown" and
https://openacs.org/doc/openacs-HEAD/postgres.html didn't seem to have reference to Postgresql 7.4 in it. Could you post a link to clarify what you are referring to please?
IIRC, Don has at least tried to install and run Oracle 9i for Mac OS X for OpenACS 5. Hopefully he has some notes that we can incorporate into the install guide.
The big thing that seems to be lacking in all the various current install guides for Mac OS X is a complete production setup for OpenACS. I appreciate that you are trying to keep things close to Linux, if I do an install, I'll try to make notes based on canonical install guide that keep track only of the differences from Linux, much like the RedHat, Debian, and Suse variants are incorporated now.