Hi Deborah,
It's been awhile 
Are you using ActiveState Perl? We use it here, except we're a windows shop. You can use the "ppm list" or "ppm query *" to what all modules are currently installed.
We recently added the Authen::SASL module using the ppm GUI utility in Windows, defined in this document: http://docs.activestate.com/activeperl/5.10/faq/ActivePerl-faq2.html
We haven't run into any problems installing CPAN modules, and actually that is where ActiveState Perl recommends getting new updates.
To install from the commands line, you can do something like: ppm install
Hope this helps,
Randall