I am working on http://jira.jboss.org/jira/browse/JBMESSAGING-341 and the first shot at it is to just to extend my installation script to extract the transitive closure of Messaging dependencies from a "default" configuration and build a slimmed-down "messaging-standalone" configuration.
I will probably only support 4.0.3.SP1 in the beginning.
A more elegant solution, however, is to create an installer profile and support this configuration starting with 4.0.4.x. Do you see things the same way?
The installer needs to be removed from the jbossas tree and pull the binary dependencies outside of the dist (seam, portal, jbpm, jms2) from the repository to build extended profiles. Installer specific configuration/customization of the services could be in the jems installer tree. This is the plan.