Look for this directory "/docs/examples/jca" and there you should find a Oracle configuration.
You can set the name of the DataSource in the JCA configuration. This name (with the leading "java:/") has to be set as the 'datasource.name'. To find the appropriate 'type.mapping' look in the "/server/default/conf" directory, open 'standardjbosscmp-jdbc.xml' file and seach for the appropriate mapping (for you it would be 'Oracle8').
Hope this helps - Andy