You need to read up on the full configuration for the listener for the full description of the mechanics of creating the certificate. In fact, you should also read up on the Tomcat connectors to fully appreciate the rerouting of requests to the secure port as required for support of the servlet directives for data security etc.
In server/default/deploy/jbossweb-tomcat.sar/META-INF/jboss-service.xml you will edit your listeners:
<!-- A HTTP/1.1 Connector on port 8080 -->
<!-- Define a SSL Coyote HTTP/1.1 Connector on port 8443 -->
The keystore file (tomcat.key or whatever you call it)you created in the SSL howto is expected to be in the conf directory for your JBoss instance e.g. server/default/conf if you are running the default instance.
Note that for your security constraints in web.xml to work correctly, you must specify in the HTTP listener to redirect to port 8443 as per redirectPort="8443" or whichever port for which your HTTPS listener is configured.
Hope that helps.