Hi Stephen,
OK... will try this. Can that update repository reside on the install DVD or install USB in a separate folder or does your autoinst.xml point at a network location?
From my understanding the update repository can be located on the installation media but we do only network installation so the following example must be adopted for a local repository.
Care to share the few lines out of your autoinst.xml?
An example for a network based add-on for opensuse 12.1
<add-on>
From a google search ( search was: add-on autoyast ) i found the following for local media based repository.
... http://blog.gmane.org/gmane.linux.suse.autoinstall/page=11
<add-on>