Jboss application server comes inbuilt with Tomcat web container. It can be located in the following location.
In this case of JBoss 4.0.2 its a directory with the name jbossweb-tomcat55.sar. When JBoss is started internally webserver is also started. mod_jk is used to establish tomcat to apache httpd server connection as you said for load balancing , sticky session etc. To deploy a web application [*.war file] it is enough if the war file is placed in jboss402\server\default\deploy\ location of jboss and started. Once JBoss starts successfully this application can accessed using the following url.
http://<machine name>:8080/<war file name without war extension>