I think you're asking how to set up a JNDI datasource in jboss - if I'm wrong, please excuse me, this will be irrelevant.
I'm using jboss 3.2.5. The details changed at some point in the 3.x series - I can't remember just when, maybe changing from 3.0.x to 3.2.x
You need a file calld xxxxxx-ds.xml
in $JBOSSHOME/server/default/deploy
(if you're not using default, substitute the appropriate name).
You can change the xxxxxx, but the file name must end in -ds.xml (possibly -xa-ds.xml for distributed transactions).
I haven't used distributed transactions, but jboss provides a number of example files in $JBOSSHOME/docs/examples/jca - oracle-xa-ds.xml should get you going in the right direction.
Hope this helps
Chris Harris
Carlisle, UK