You could use the AS7 management API directly. There are a few options: Either you use the java API, execute operations from a bash script using the CLI or the http/json API from a scripting language of your choice.
This page describes the available clients: https://docs.jboss.org/author/display/AS71/Management+Clients
I looked at the commands, couldn't find one for adding servers!
something like /host=master/server-config=newServer:add(group=my-server-group,socket-binding=standard-sockets,socket-binding-port-offset=150)