It is possible to do this but at least one of your Tomcat instances will need to be a standalone version - download it from the Tomcat site.

You will also need to do more work, such as making the JBoss client libraries available to the standalone Tomcat version - i.e. putting the libraries in the Tomcat shared/lib directory. To connect to JBoss EJBs, you will need to configure the JNDI initial context for your web application as you would if you were a remote client to the EJBs. You will also need the client JARs for your EJBs in a place where your web applications can reference them - either in the WAR on in the shared/lib directory.