Sorry to state the obvious but you need to install them. e.g.
http://pkgs.repoforge.org/perl-DBD-MySQL/
In general you'd do well to install the rpmforge release for your system
http://repoforge.org/use/ then just grab each package through yum. Note that as you're not installing from rpm / yum in the first place, there's no decent framework for dealing with these automatically. If you install RT via yum then this will all be dealt with automatically. It can be found in the EPEL repository as "rt3" from the looks of it.
to do that, install this
http://download.fedoraproject.org/pu...5-4.noarch.rpm and this
http://pkgs.repoforge.org/rpmforge-r...l5.rf.i386.rpm and then just run "yum install rt3" and that *should* work fine. Only exception is if the repo's are not enabled by default, in which case look at the appropriate files those two packages put in /etc/yum.repos.d/ and set "enabled=1" or enable them temporarily using yum command line options (see manpage)
Oh, those two release packages are for el5 *i386* so if you're on a 64bit system then you'd need to x86_64 equivalents.
