Chance Garcia has a recent post to his blog showing how he fixed an issue with his MAMP install involving development of a SSH wrapper he developed and some testing out of PHPStorm and PHPUnit.
One thing I can say is that, even though I use a convenient app like MAMP PRO to set up my local development environment, I'm glad my sysadmin-fu is up to snuff enough to fly without the conveniences because after this ordeal, I feel like I might as well have made my MAMP stack from scratch with all the hoops I jumped tonight.
He shares a few of the things he discovered along the way like: the location of MAMP's "pecl" command, an error caused by a bad pear.conf file, doing custom compiles of PHP and libssh as a fallback and getting the extension to work in the CLI PHP version too.