there will be more documentation available as part of JB4 on doing this. code for JMX remoting will be part of that release.
I also want to do the same thing. Is there anything I can do now (perhaps using JBoss 3 or not) so that I can easily migrate to JBoss 4 when its ready. Basically, I want to manage several distributed applications using JMX (starting and shutting down) and seems like using JBoss as a container could be useful?