When configuring an Scripted OS Install (SOI) job in Ghost Solution Suite, there is an option to use a custom unattend.xml file for the job.
This kb will go over the required components needed in that file for the SOI job to be a success.
The Vista_unattend.xml that we place in the following path is a good start:
C:\Program Files (x86)\Altiris\eXpress\Deployment Server\Deploy