We had same issue.
I am not sure there is any way to configure different port for for different web application if all web apps are resideing single JBOSS instance. Instead you can enable seucrity for each web application. Create different username and password for each.
To resove this issue I am using same port for different applications with different username and password.
Also You can create virtual host for each web app.
Please ignore if my reply won't help.
subject: how to setup separate ports for web applications