well not many people worry about seperate class loaders when they are just getting started. Renaming war to ear won't quite work.
Maybe try for some hints here http://www.yorku.ca/dkha/jboss/index.htm
Or for more general stuff try looking at sun's sites for ear file formats etc.
You need to package your app as an ear and add a jboss-app.xml which declares the <loader-repository> element. See the 3.0 Admin book for details.