Where did you get this code? I don't see it as part of PPM::Repositories. As you say, the code you are running seems geared towards an older version of PPM. Your options include running PPM and figuring out what the actual command to add a repository is, and using that.

Regardless I can't find a 5.16 repo with this module for the 32bit Windows platform. The README has instructions for building this yourself on Windows.