Hi,
lot of answers... but
First what JBoss do you use,
JBoss4 => you need to activate the ServiceBindingManager within the server/.../conf/jboss-service.xml
you can use ports-0? configuration
JBoss4 => there is a active configuration you can use it, it will shift the ports wit an offset.
You should read http://community.jboss.org/wiki/ServiceBindingManager for detailed information.