> I can't use yum to install ANYTHING, unless I can select versions of software.
You CAN yum install a selected version:
yum install httpd-2.2.15 mysql-5.1.66
> So, I'm learning how to build my own AMP stack, and will likely host the repo myself.
That's probably better than hardcoding a specific version - install the lastest version that's in your repo.