Ok, I just finished going over this whole document and here's what I found. The most important and problematic stuff I listed closer to the top, and things get a little more knit-picky towards the end. Forgive me if I seem like I'm being picky about some of this stuff. I really like the work you've done, and I hope my comments will help make this document even better.
First, let me repeat what others have said about the location of MySQL. I'm also on RH9 and I believe the way Redhat installs everything, MySQL is placed in unusual directories. My stuff was located here:
This is also true with EZMLM where you tell us to change the path under sub_mysql/conf-sqlld, and also under the qmailadmin section where we check to see if /home/vpopmail/etc/lib_deps contains the lines you specified. Also on this line, I had -lcrypt, but you didn't mention anything about this, or whether it's OK.
When installing courier-imap, I had some big problems. Checking inter7's website, they specify that you MUST run "configure" and "make" as a non-privlidged user. Your instructions didn't say anything about this. When I did that, everything worked fine.
For the qmail startup script, I had some problems. When I ran this script for the first time, I kept getting a bunch of lockfile errors. I ended up changing this to the script used in Life With Qmail, and everything got better. I'm not totally sure if that was the reason for the errors, but maybe other people can confirm this from their own testing.
Since I am on Redhat, Spamassassin came pre-installed as an RPM. People should remove this if they have it. You also tell us to edit /etc/init.d/spamassassin and change a couple of lines. I didn't see the lines you were talking about, so I skipped this part. When I ran the tests to see if it worked, you said we would get "hits=1000" but instead I got "hits=6.9". Don't know if that's bad or what. I also didn't see anything about "tests=GTUBE" or "autolearn=no". The version you said would be 2.60, but mine said 2.55, which makes sense because that's the version we installed. Not sure where you got 2.60.
Under section 11.1 you tell people to echo "tech" into the alias files. Maybe it would be better to tell people to replace "tech" with some other account of their choosing. Also, you said for us to edit /var/qmail/users/assign and add a line. I believe this done automatically when you use vpopmail's vadddomain command. I think the only thing the user must do is make sure the period is there. Otherwise, they can use vadddomain to accomplish this.
I had a few problems downloading from the various wget commands. I don't know if the sites were temporarily down, or permanently down, so I figured you could look into this and see what you find. Here are the ones I had problems downloading:
The errno patch for daemontools
Autorespond from inter7's website
gdbm from mirors.kernel.org
In EZMLM, it's better if you use mv -f so you don't have to confirm everything.
In the Daemontools section, you said we should comment out the last line from /etc/inittab (the svscan line) but you didn't say later on that we should uncomment this line. I forgot and had to come back later and uncomment the line.
In section 3, TCPServer, you talked about installing the development ssl lib from cr.yp.to. Not sure what that was or where to find it, but I didn't install anything apart from what the directions specified, so I don't know if I really needed this or not.
Also, your numbers are out of step. You've got the "Files" section and the "References" section both labelled as #20.
Other than this, I found the guide to be very complete and extremely useful. I hope that some of these tweaks will help to make it even better.