Yeah, I went the PAR route for deploying Perl apps on multiple Win32 desktops. The code I inherited had some rather yucky 'auto-install-if-the-module-is-missing' code tucked away in a BEGIN block.

I don't remember exactly how the code went but it was something like this

BEGIN {
   eval { require FOO::Bar };
   if ($@) {
      system("ppm install FOO::Bar");
   }
}
[download]

PAR is by far the better way to go :-)