I asked the JBoss users group about the location of a method called getUnderlyingConnection().
They advised looking for:
org.jboss.resource.adapter.jdbc.local.LocalConnection in older versions of JBoss.
I've looked through every .sar file I could find in JBoss 3.2.1 and I can't find either of these classes.
Any suggestions would be welcome,
Thanks in advance,
jboss-common-jdbc-wrapper.jar in your server//lib directory
but you probably want to have a look at the source code instead...