If you're not going to build Apache from scratch with mod_perl, you might as well just install mod_perl via rpm. There are rpm's for RedHat 6.2/mod_perl-1.21 available on the RedHat mirrors.

-fp

Update: Chmrr makes a good point in his post, but I'm not aware of any problems with the mod_perl rpm. I use it in many of my machines without any problems. Perhaps some more detail?