It's not quite the same thing you're talking about but I have something to create modules for running unit tests. It lives at https://github.com/kabir/jboss-modules-surefire-plugin. It is sort of documented at http://community.jboss.org/wiki/JBossModulesSurefirePlugin.
Getting this working with arquillian so that no bootstrap classes are needed on the runtime classpath is work in progress.