[Zope] Newbie question about installing modules

Hi there, I've just installed Zope and Plone and I'm trying to install additional modules (like the VisualEditor module). It has to be copied to the lib/Python/Products directory. When restarting the zope server, it generates an error. I couldn't find any documentation about how to install the module (other than: "install in the normal way"). I suppose I have to run some kind of script to install the module properly. Any help will be appreciated !!!!!!! Chris.