How do you configure a VM image to run a custom script ONCE on startup?

Hello,

I am creating a Windows image that will be deployed to the VM depot: https://vmdepot.msopentech.com/List/Index

When the image is run for the first time, I'd like to run a custom script.  However, I only want this script to run the first time the VM is run (and never again).

How would I do this?

Thanks!

Matt