FWIW, I had used
likely available elsewhere too.
Used that on Slackware 12.0 and before (my 12.1 isn't up yet -- just installed, runs, needs a bit more configuring at this point).
cpan2tgz is not that difficult to use. I used it as root.
Resultant pkg also can be installed on another box with same ver. Slackware.
As to your .pm's from different ver's of Perl in different locations: I doubt that the next be an issue on Slackware (Slack seem to hardly or not use Perl to manage the sys ie some config's, etc. when parts of sys patch/update/change).
Different story on, what was it, Fedora Core something (2, 3, or 4) -- it's been a long while since I've even used Fedora. Back then, it's (Fedora distro) default in /usr/bin/perl
Well, (on that Fedora) I came along and built my own Perl from the latest source in /usr/local/bin/perl
Then, due that I didn't want to change my shebang lines in my own Perl scripts
I decided instead to symlink from /usr/bin/perl > /usr/local/bin/perl
All is fine, new Perl works super.
Until some new (security updates, etc.) patches to Fedora available.
Oop, we are broken now (the sys uses Perl for some of those to get updated/patched) and it happens incompatability and/or "not found"
From that, at least I learned what not to do.