After some more investigation, I discovered the SAR. I put myWebApp.war and META-INF folders inside mySAR.sar. The META-INF contains a jboss-service.xml, which looks like this:
Now, I can take out the similar XML in the default/deploy/user-service.xml. However, I will appreciate very much if someone confirms that I am meeting my goals the "right" way.
yes SAR is the packaging you want to use when your deployment unit includes mbeans.