[Zope] PYTHONPATH

I would like to do some Zope product development outside of the main Zope environment and need to set my PYTHONPATH correctly to pull in all the right modules. I have Zope installed at "/zope" and my path is currently: PYTHONPATH=zope/lib/python:zope/bin/lib: When I attempt to compile the line "from Interface import Base" I get an error that the module does not exist. I am following a tutorial in the zope developers guide... I have also tried importing other modules to no avail. Any ideas? Thanks.