I can't answer your question, but Liferay doesn't do this very well either. Nor integrate with Oracle. Its the reason we passed on Liferay and embraced JBoss Portal. I sure miss JBoss Portal.
What product is the continuation of the JBP-type product?
Its possible to take GateIn and install in on another Tomcat instance. We don't test that, but it should work. Just compare the Tomcat version of GateIn to the normal Tomcat version, see what changes are made and make those changes to your own instance of Tomcat. It will mostly be extra jars and wars (and a few configuration changes).
We don't provide a standalone zip of GateIn or instructions on how to install it in another server instance. And there may be issues if you are copying it over to a version of the server which is not the same as the one that GateIn uses.