Is there any documentation on how to use this feature? Is this utilizing the ejb-jar.xml and jboss-ebj3.xml descriptors or something more?
I'm not sure about documentation but there is an example of such an deployment xml file, test-jms.xml, in the testsuite.
There is a schema document in JBOSS_HOME/docs/schema/ called jboss-as-messaging-deployment_1_0.xsd
It is also important that the file name end in "-jms.xml".
A description of how to deploy a datasource via deployment descriptor can be found in this blog post and the deployment of JMS Destinations is similar: http://planet.jboss.org/post/jboss_as_7_1_0_final_thunder_released_java_ee_6_full_profile_certified