Is it possible to handle this with ppd?

Yes - for an example of how this is usually done see the ppd file for Crypt::SSLeay at http://theoryx5.uwinnipeg.ca/ppms/Crypt-SSLeay.ppd. Note the <INSTALL EXEC .... </INSTALL> command and the install script that it calls (which installs the 2 SSL dll's) at http://theoryx5.uwinnipeg.ca/ppms/scripts/install_ssl.

Another alternative to that is to place the dll in the blib/script directory of the ppm binary - in which case the dll will automatically be placed in perl/site/bin (unless there are permissions issues which forbid it).
Update: Actually, it might go into perl/bin, not perl/site/bin ... not sure offhand.

Cheers,
Rob