Why don't you use phpopenTracker (available at http://www.phpopentracker.de) It's a very powerfull, PHP-written framework, which can easily be added to any eZ template.
If you insert a specific tracking-link into a template, you can track nearly everything.
it should also be possible to add phpOpenTracker as a module to eZ publish, so that you can configure and read your stats via your eZ administration interface. I think this will be a good idea to develop such an extension. What would You say?
