You will need a utility called "PeToUSB".
http://gocoding.com/page.php?al=petousb
Run PeBuilder as normal, but just create the image file (Tell Pebuilder where to save it on your C:\ drive). You do not have to burn it to a CD.
When you have created your 'Image' file, Run PeToUSB to transfer the 'Image' file (I hope you remembered where PeBuilder put it

) to the USB Drive and you are done.
Insert your USB Drive into the chosen computer and Boot up (your computer bios has to be set to boot from the usb...)!