Hi there folks.
With the final release of Backtrack 4 Final right around the corner, I thought I would get ahead of the curve and update the how-to. I have access to the pre-final via the Informer.
The updated version is where the original Beta instructions used to live. I have copied the Beta instructions to a new page. They can be found here.
So here you go.
http://www.infosecramblings.com/backtrack/backtrack-4-usbpersistent-changesnessus/
-Kevin