Changing the database for JOnAS installation

["NICHOLLS T Ext ROSI/DPS" <tnicholls.ext@xxxxxxxxxxxxxxxxx>]

I am trying to change the database used for the eXo platform. The problem is 
that the doc that exists 
(http://www.exoplatform.com/xwiki/bin/view/Main/databaseconfiguration) is not 
relevant for my JOnAS installation.

How do I change from the default HSQDLB to Oracle?

Cheers,
Thomas