a little update: we did it.
We derived an architecture with multiple scoped ear files hosting portlets and local/remote ejbs.
the portal is made up of portlets that get connected via a stateful session bean being its controller.
These are connected as remote or local injected sfsbs. The tree of injected sfsbs creates a tree of portlets
which make up a portal page.
Thus we created a portal-based application that is able to show the web interface to various business processes.
Great technology, thanks all at Redhat/JBoss and to the community!
Armin Vogt