My customer asked me for a solution, and he described the process like this:
1. Technician walks to the desk with the USB key
2. Runs some batch file from the USB key
3. Data gets backed up to this key
4. Tech images new computer with this key and data gets automatically restored
So here is the solution for that.
1. Create a Media under deployment share Advanced Configuration like you'd do for CD/DVD media deployment
2. You can find sample rules file customsettings.ini in Deploy\Control\customsettings.ini
3. Create a new custom TS calling it USMT, overwrite TS.XML with the file from attached archive from Deploy\Control\USMT\TS.XML
4. Copy batch files from the archive to the root of your Deployment Media share. Now you're done with the backup part. To do a backup of the system you'll need to run SaveState-WinXP.cmd
5. You will need to modify your existing TS. I created a dummy TS so you can copy/paste it from your temporary TS. Create a new TS, and replace TS.XML with the file from Deploy\Control\DUMMY\ts.xml
6. Edit this TS and copy and paste everything from it to your deployment TS right under 'Capture Image" folder
7. Remove SET USMT3 to YES step (third one in this folder) if you deploy Windows 7. Do the same thing in customsettings.ini. Rename SaveState batch file and remove USMT3 from it.
That's it. I have not figured out how to make the same media usable as a CD/DVD, it will fail after figuring out that DataStore is Read Only.