I'm having the same problem. I'm trying to expose my C:\project directory through Tomcat using the URL http://localhost:8080/project. I'm adding this element to the Host element of C:\jboss-4.0.0\server\default\deploy\jbossweb-tomcat50.sar\server.xml:
<Context path="/project" docBase="C:\project"/>
It works in Tomcat 5.0 standalone and JBoss 3.2.7RC1, but does not work in JBoss 4.0.0.