If you use JBoss 3.0.1, the access has changed to http://localhost:8080/jmx-console. Which means you use the port that Jetty uses. If you want to access console on a port different from other apps, I suppose it means figuring out how to start up JBoss with 2 instances of the web service. Not sure.
If you crack open jmx-html-adaptor.sar
the config is in META-INF/jboss-service.xml
In jboss.jcml edit the 'Port' attribute,
This works fine in JBoss 2.4.4.