Hibernate version:3.1.3
Is there any reason why JTASessionContext does not implement a bind and unbind method the same way that ThreadLocalSessionContext does?

I have been looking at the JTASessionContext implementation and it uses a map of (transaction, session). It will be a map of all transactions for the different threads. If I want to manipulate the map and bind and unbind a specific session to the transaction (for long conversations) I need to get a handle to the instantiated JTASessionContext of the specific SessionFactory.
Can I obtain handle to that object?
Is there a good reason not to be doing any of this?
Is there a reason not to use JTASessionContext for long conversations?