Subsitute the NoTxConnectionManager class for LocalTxConnectionManager in the mbean configs. I think you'll have to remove the TransactionManager attribute as well.
Connections you get from this datasource will always have AutoCommit on. Each time you get a connection you will have to call setAutoCommit(false). (these autocommit settings are sent to the db only if you actually do work in the new autocommit setting, so this won't result in extra calls to the db).