I am trying to run server for iphone using http://www.raywenderlich.com/3932/how-to-create-a-socket-based-iphone-app-and-server
My machine is mac 10.6.8 Python versi
Off the top of my head you can use easy_install for this.
You will need the python-setuptools then you should be able to use
easy_install zope.interface
If I remember correctly however twisted should be installed as part of OS X python install. Do a quick Google for installing zope.interface for Mac OS X. As twisted is such a widely used library there is plenty of information out there.