Answer: To pass parameters to a portlet you must give a
unique name to the portlet instance on the target page; simply giving a
portlet a unique name in the UI is not enough.
Parameters are not visible to JSR 168 compliant portlets
if the URL does not point specifically to that portlet.
The way to assign a unique name to the portlet on the page
is through XMLAccess
Here is a Tech Note on how to do this.
Advanced URL generation in themes and portlets