tech support? Why? You can indeed but do not have to, b ut thank you for reminding me of this question and helping out. ;-)
First of all, the jBPM core itself doesn't do anything with identities. It just takes the actorID as a string. The identity module is a simple user/role/organisational component.
If you already have info in a database, have your appserver connected to that database, and use the demo webapp, you can slightly adapt the Loginfilter to fill the userBean from the request.getUserPrincipal(). Besides that, you can write your own assignmenthandler that connects to you database and does assignments e.g. based on processvariables or anything you choose.
hth a little, since I now donated 30 minutes of my FREE time