ArsDigita at one point wrote the "Hitchhiker's Guide to the ACS" which described a good chunk of what you want to write about, especifically, the RH 6.2 installation.
I gave a presentation on basic Linux security that teaches why and how to disable services, among other things. I need to add a couple slides, then I'll post the link here.
And lastly, this would be great to be contributed to the OpenACS docs. Whatever format you write it in (as long as we can export to HTML). Doing it in DocBook is a plus, but don't get stuck there.
