The kind of session (transacted vs. non-transacted) that jBPM uses is not configurable: it is hard coded in JmsMessageService.java
session = connection.createSession(true, Session.SESSION_TRANSACTED);

That line was changed as follows to make async continuations work with Weblogic.
session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE) ;

The reason is that JBoss and Weblogic handle JMS sessions within a JTA transaction just in the opposite way. For details read:

Weblogic: http://e-docs.bea.com/wls/docs103/jms/trans.html#wp1025537
JBoss: http://www.odi.ch/prog/jms-tx.php