Every SCAr release has one of the RAAr library releases as one of its dependencies. So you can jusy download or build and deploy scar.war into your JBoss AS. It's as simple as that. The SCAr wiki pages contain the installation instructions.
I should tell you though that we're almost ready to release the next version of SCAr which will run against Alfresco 3.3. We're planning on releasing a version for Alfresco's Community release and a separate one for the Enterprise release.