While this isn't a solution it might help. I'm dealing with some of the same issues. I just found out a simple way to view JBoss' JNDI tree:
* Go to http://localhost:8080/jmx-console
* Search for service=JNDIView
* Click on that link
* On the page that comes up click on the Invoke button beside the list() method
i can see mysqlDS in java:
So how do i lookup this object ?
Could you post your mysql-ds.xml and persistence.xml files?