Hi JMS97,
We have researched methods of doing this and found that using the Automation Folder approach worked for us and a customer of ours.
We then use a scripting task to change the boot order and restart the machine. This then forces the machine to boot into the automation folder and reimage.
There are options to run custom scripts at different points of the boot process also, this could complete some of your other DS-related tasks when it is booted into WinPE and not connected to Altiris over CEM at that time.
Thanks