you need to access the quartz JMS service, first follow this article : http://community.jboss.org/wiki/HowtoconfigureaQuartzservice
after getting Scheduler instance you can call this method :
you can also get other information after getting this instance,
hope this will help u.
I suppose you want to have the number of messages in the queue if your MDB is called, right?
You might check the QueueBrowser class.
But the information is very temporary because of other parallel running MDB's.
What is the reason to have such information?