Current specj module is tested against current Branch_4_0.
If you are trying 4.0 release, try changing org.jboss.ejb.plugins.cmp.jdbc.metadata to org.jboss.resource.adapter.jdbc.metadata in jboss-service.xml
I am using Jboss4.0.0.
I tried your option,Even that says ClassLoaders not found!!
I had the same problem with JBoss4.0.0. There the class MetaDataLibrary is missing.
JBoss 4.0.1 works fine and the class is present there in jboss.jar