I'm presuming you've set up everything according to the example found here
http://www.hibernate.org/66.html
If you have, then you don't have to manually create the configuration object and add your classes. All you have to do is
Code:
InitialContext ctx = getContext(); //some method that creates your ctx
SessionFactory sf = (SessionFactory)ctx.lookup("java:/hibernate/HibernateFactory");
Once you've got a reference to the SessionFactory, you can create sessions and do whatever you want to with them. If this isn't working for you, then you may have missed something in your MBean setup.