Which version of JB are you using?
Looking at 3.x: the simplest way to do this is to deploy a ???-ds.xml for every datasource you like to use.
You can include multiple configs in a *-service.xml (3.0.x) or *-service.xml (3.2). You just have to make sure that the jndi-names are unique and (for the *-service.xml file for 3.0.x) that all the mbean names are unique.