From README:

ZOPE:

You should install this product as usual. Unpack the archive with all contained directory information into your Zope products directory <ZOPE>/lib/python/Products or <INSTANCE_HOME>/Products. Restart Zope.

PLONE:

Create an instance in the root of your zope server through the zmi. (Add->mxmCounter). It will automatically get the id "mxm_counter".

Already built into templates...