External Methods for Plone/Zope

I have two instances of Plone running on a server - their locations are /usr/local/Plone/Inst1 and /usr/local/Plone/Inst2. I'm trying to setup external methods, but am having a difficult time figuring out where my "Extensions" folder should be placed. It seems that where ever I place it, the ZMI never sees it. I have tried:

/usr/local/Plone/Extensions /usr/local开发者_如何学JAVA/Plone/Inst1/Extensions

...and various other sub-folders within the "Inst1" directory. When I add an external method, I've tried adding it at both the root of the ZMI ("/") and in the Instance folder ("/Inst1/"). When I add it to the root, I get a message that says "The specified module, demo, could not be found." When I try to add it in the instance folder, I get an error page that says "This page does not seem to exist..."

It appears that the ZMI is failing to find that file ("demo.py"). Is there a particular place it should be stored?

After looking over documentation from Zope's site (and numerous tutorials), it should be in the "Zope" folder - but I don't have any such folder (nor does any folder named "Extensions" exist on the file system, other than the one I created in the "Plone" and "Plone/Inst1" directories).

Depending on what version of Plone you have installed will change this, but it is likely something like:

/path/to/plone/install/parts/instance/Extensions

Or

/path/to/plone/install/parts/client1/Extensions

You're probably better off putting the external method in a product though since placing an external method in it's "parts" instance folder will mean it will be wiped out every time you run buildout. Then if you're going to make a product out of it, you might as will do a traversable view utility like "@@plone_context_state" and "@@plone_portal_state" which is usually a better way to do it.