Are you asking whether you can serve up WML pages with JBoss without Tomcat?
Well, to support serving of WML pages, you have to use some form of Web Container. JBoss currently offers you two choices - either use Tomcat, or use Jetty. The default package for JBoss v3.0 ships with Jetty fully integrated.
As to your question of supporting 1000 consecutive users - of course, capacity and performance is derived from a number of different areas. However, I believe supporting 1000 consecutive or 1000 concurrent users is definitely possible - it all boils down to how your application is architected, and your deployment model.