fedora 12 linux kernel 2.6.32.16-141.fc12.i686.PAE
core2quad, 8GB RAM

firefox-3.5.15-1.fc12.i686
perl-5.10.0-96.fc12.i686

MozRepl: latest from git as of 2010-12-01 (tried both stable and snapshot)

WWW::Mechanize::Firefox latest from cpan as of 2010-12-01
WWW::Mechanize latest from cpan as of 2010-12-01

dependencies:
# I try to install from Fedora yum rpms when possible
js-devel-1.70-8.fc12.i686
perl-parent-0.223-1.fc12.noarch
perl-Class-C3-XS-0.13-1.fc12.i686
perl-Algorithm-C3-0.08-2.fc12.noarch
perl-Class-C3-0.22-1.fc12.noarch
perl-MRO-Compat-0.11-2.fc12.noarch
perl-Text-SimpleTable-2.0-2.fc12.noarch
perl-Carp-Clan-6.00-5.fc12.noarch
perl-IPC-Run-0.84-1.fc12.noarch
perl-Data-Dump-1.15-1.fc12.noarch
perl-JSON-2.15-5.fc12.noarch
perl-Net-Telnet-3.03-9.fc12.noarch
perl-YAML-Tiny-1.40-1.fc12.noarch
perl-PAR-Dist-0.46-1.fc12.noarch
perl-File-Remove-1.42-3.fc12.noarch
perl-Module-CoreList-2.17-96.fc12.i686
1:perl-ExtUtils-CBuilder-0.24-96.fc12.i686
1:perl-Module-Build-0.3200-96.fc12.i686
perl-Module-ScanDeps-0.95-1.fc12.noarch
perl-Module-Install-0.91-2.fc12.noarch
perl-Spiffy-0.30-11.fc12.noarch
perl-Algorithm-Diff-1.1902-8.fc12.noarch
perl-Text-Diff-1.37-2.fc12.noarch
perl-Test-Base-0.58-2.fc12.noarch
perl-CPAN-DistnameInfo-0.09-1.fc12.noarch

Non-Fedora-rpm cpan dependencies all latest as of 2010-12-01