I installed perl 5.8.9, 5.10.1 and 5.12.1 (from source) in /usr/local/perl5 (in that order). Do not accept the defaults, install it the long way. Due to the fact that a) I had the time and b) I had the disk space, I made sure that each version did not reference the earlier versions. This way, I have a "clean" install of each (even though they reside in the same upper level directory. You will find perl5.8.9, perl5.10.1 and perl5.12.1 executables in the basedir/bin directory.

Then I started with the base perl install (using autobundle) and then used the resulting snapshot file to install all base modules to each version (example: "perl5.8.9 -MCPAN -eshell" then "install Snapshot_2010_08_03_01").

Now, you can add whatever modules you want from CPAN.

Do not touch the system install (in /usr/bin and /usr/share/perl5). Simply set your non-root path to include /usr/local/perl5/bin before /usr/bin or use explicit paths. Since you defined the base directory during the install, the PATH environment variable (to find the perl executable) is the only one you need.

Good luck with your project :-)

Update: To get back to base on your system, do "yum reinstall perl*" (I don't use the -y flag, mainly so that I get out of the habit). If you get into the habit of something like "yum -y reinstall XXX", it is easy to forget and do something like "yum -y remove XXX" which will do exactly what you tell it to: remove the package and all of its dependents. As was noted above, using yum to remove perl will remove the X server among other things without prompting. That will ruin your whole day.

Update 2:Clarified warning on yum -y.