If your sub-web.xml file works...can you post it? I obviously must not understand a part of the documentation as I'm declaring my alternatedocroot_1 in the admin panel. I added it in sun-web.xml as well to see if this would fix the issue. But it didn't.
[Message sent by forum member 'twitchman' (twitchman)]
http://forums.java.net/jive/thread.jspa?messageID=360867