I have had very similar problems at work, where ppm would not work. The workaround I used was to download the files I wanted manually (the paths are pretty easy to figure out), then in ppm I added "." as a repository (ie, the current dir) and disabled the default repositories. Search and install worked fine. You'll need to get the .ppd, the .tar.gz, and the install_* file, if there is one (eg, if you wanted Crypt-SSLeay, you'd get install_ssl, Crypt-SSLeay.ppd, and Crypt-SSLeay.tar.gz from whichever repository you want)

Of course, I'm assuming that there's a ppm for macs... possibly an incorrect assumption. I know it works under linux and solaris, so I don't see why it wouldn't work on X/jag.

Some older ppm versions don't allow you to configure repositories, but >= v3.1 will.

Good luck!