Oh, you are not sounding argumentative or obnoxious, I'm just really busy.
I've never set up a connection pool using just the JDBC driver, so I'm not sure how it works in practice. And the more I think about it the more I think that the pool is available only to the one app, and not across multiple apps. But then i have been wrong about stuff like this before!
The idea to set up two data sources in JBoss AS, one for each credential, would work. Your update requests would use the update data source, and reads would use the other data source.
And we are still waiting on someone with more Hibernate expertise to comment on schema changes...