This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Have you checked out EJB by OReily. I believe they have a chapter that talks about the EJB 2 and 3 beans interoperability. That might help you.
I have one doubt though, when you migrate your entity beans to JPA entities, would you be modifying the existing code base? If yes then why not take annotations?
subject: how to migrate EJB 2.0 to EJb 3.0 using XML descriptors