Sounds easy enough, but not all motherboards will boot all USB sticks; in fact, you are lucky if you find a working combination :((
It's installed during setup, but versions before 1'st may 2005 wouldn't work
c:\Program Files\Snapshot> Snapshot networkbootdiskette.sna u: (where u: is your USB stick)
correct some parameters on the USB stick
c:\Program Files\Snapshot> Snapshot -!checkboot HD2 (or whatever drive your stick is)
and answer questions with 'Y'.
Better now then in an emergency ;)