What do you mean by obtaining the path to Perl from the PPM prompt? To get Mail::Sendmail with PPM, just start up PPM and type "search *". Wait for the results (it might take a long time) and look through them for Mail::Sendmail.
Type "install Mail-Sendmail" or "install modulenumber" and it installs automatically into the correct folders.
Since you're on windows you only need to go to CPAN to look up module information, not to download modules.