I would suggest that you use an external static content directory http://wiki.jboss.org/wiki/ExternalDirectories, but because you cannot do exploded deployment, that probably will not work for you either.
Looks like what you are asking for is a way to add or modify the content of a WAR file without changing the timestamp on the WAR file or without the WAR file being redeployed. Hmm, maybe you could turn off the hot deployer. But then you would have to either manually deploy new apps or restart JBossAS to deploy them. But that would prevent the WAR from being redeployed when you update it.
Peter, thanks for the feedback... seems like I am a little backed into a wall on this one and the only option is to deploy the exploded war file.