Deploying portal is rather easy. Two steps are required: 1) create shared library with portal dependencies and 2) deploy war (or exploded war).
I have attached the server.xml used for deploying.
But there are some problems:
+ all shared libraries must be defined together as one library i.e. there is no inter-management between shared libraries (internal liberty stuff, not a big deal)
+ liberty is not recognized as an app server by the portal, so deployer (and few other features) is not working
+ when you login, the whole admin bar is missing; looking like combo servlet issue - so practically, portal is unusable.