Copy $JBOSS_HOME/lib/endorsed/xercesImpl.jar into $JBOSS_HOME/client directory. This is to resolve an issue in JBoss4.2 about a class not found.
Copy $JBOSS_HOME/server/default/lib/jboss-saaj.jar to $JBOSS_HOME/lib/endorsed
did you solve your problem? I have exactly the same with JBOSS 5.1.0GA JDK1.6 compiled. I'm not able to call the webservice with the "setProperty must be overridden by all subclasses of SOAPMessage" exception.