(I haven't tried this)
(I don't know why you'd want to do this)
In the outermost mbean, replace the code attribute so it uses NoTxConnectionManager instead of LocalTxConnectionManager. Remove the transactionManager tag.
The motivation for this comes from weblogic where they have JDBCTXDatasource and JDBCDatasource config file settings. The non-transactional variety is reportedly more efficient. Consequently, most weblogic expatriates feel queazy about using the transactional variety for everything. When porting to jboss that issue comes up almost right away.