Just some notes about installing wre on a system that already has perl - NO GUARENTEES:

Having perl and wre's perl installed on the same machine will not be a problem. You'll have to remember to do a setenvironment.sh when working with wre.

EXCEPTION: on RHEL/CentOS, if you do setenvironment.sh, you won't be able to use yum. So be careful about putting setenvironment.sh into root's .bashrc or .profile

Using wre's perl exclusively:
If you wanted, you could remove the system's perl and then creating softlinks from /usr/bin/perl , /usr/bin/perl5.10.0, /usr/bin/perlbug, and /usr/bin/perldoc to /data/wre/prereqs/bin's perl stuff respectivly.

Another approach is to patch the following use lib statements into WebGUI.pm imediatly after the use strict; line:

use lib '/data/wre/prereqs/lib/perl5/5.10.0';
use lib '/data/wre/prereqs/lib/perl5/site_perl/5.10.0';
use lib '/data/WebGUI/lib';

and  in preload.perl

use lib '/data/wre/prereqs/lib/perl5/5.10.0';
use lib '/data/wre/prereqs/lib/perl5/site_perl/5.10.0';

Considerations: If you do choose to use wre's perl, you may come up against binary compatibility issues: WRE's perl is compiled with different libs.