Stopping remotely from the command line can be done with the shutdown.sh script, by pointing to the right host and port. Or, using jmx-console, you can stop by invoking the shutdown method on the Server MBean.
If you have *nix boxen, starting remotely can be done using the usual rsh, rexec, ssh, or any other command that can execute something on a remote box:
rsh user@host /path/to/jboss/bin/run.sh
Not sure how to do this in the Windows world.
Once installed as a service on Windows XP you can use the 'Computer Management' console to remotely start and stop service.
All version of Windows back to NT 4.0 that supported services have a mechanism to remotely start and stop services.
We use the Java Service Wrapper on Windows to run
JBoss as a service (http://wrapper.tanukisoftware.org).
This comes with a couple of MBeans you can deploy that allow you to interact with the owning Windows service. The MBean provides methods for re-starting the JBoss VM. These can be invoked from the JMX console or by the JMX invoker.
The service wrapper is alos availabeon various UNIX platforms. I think the same functionality is then available.