I do this by using multiple (each of which are the same) server configurations in different directories.
In your Jboss dir your the servers dir. Copy and rename your working server directory to another directory.
Start your server with the command-line run.bat (Windows) with parameter -c
if (in servers directory) you have:
you can start server2 instance by doing a "run.bat -cserver2"
Hope this helps
I forgot to mention.
In each of the diretories for your servers, you have (at least) to change colliding port numbers for services: JNDI, Tomcat, etc.
I've almost completed an article on clustering multiple instances of JBoss 4.0.2 which includes detailed instructions on the ports that need re-mapping to allow multiple instances to co-exist.
It might be of help to you.
please read the forums and wikis before entering a topics in the forum.
This question has been asked so many times...
have a look at :