This was to be a command-line interface for finding, downloading, building, and installing PGXN extension distributions writtn in Perl. But then Daniele Varrazzo beat wrote one in Python. So this project is defunct. What you want is his pgxnclient project. It's even better than what I would have done.
statyan/pgxn-client
Never implemented client for downloading, building, and installing PGXN distributions.