If you setting up the cluster environment on single machine(example : on your laptop) then you need to create three different nodes which should be running on different ports like 8080, 8081 and 8082, after you create these nodes then if you place your war file inside the webapps folder (hot deployment) the app will get deployed on other nodes(other webapp folders) automatically.
I have done this with
Jboss server and it works fine.
Thanks, Gopi