If I am understanding the question, you'll have to bind the factory objects into the JNDI tree yourself, using Context.bind(). An MBean is a good place to do this. Check out the MailService MBean (in varia) for a good example.
I saw something in the manual that seemed to be doing the same thing. It was a simple MBean example that bound a name to a hashtable. If I have to do this I suppose that's okay. So there's not an existing MBean that can take a name & classname pair, with some initial args, and create an object & bind it for you. I'm surprised it's not there, which makes me think they have a good reason for it that I'm not currently seeing.