I'm using Jboss 3.3 M2 and this version has a wizar to Birt 3.7, but I in order to work with b: tags I had needed to add the jar's and tdl's described here and this to my web.xml
<servlet>
<servlet-name>JBoss BIRT Servlet</servlet-name>
<servlet-class>org.jboss.tools.birt.servlet.JBossBirtServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>JBoss BIRT Servlet</servlet-name>
<url-pattern>/embed</url-pattern>
</servlet-mapping>