cp /Volumes/USBDrive/InstallESD.dmg /Volumes/Macintosh\ HD/, where you replace the paths with the ones found in step 2) In which case use 2 USB drives (one to copy the InstallESD.dmg from the PC and one to restore it to and boot from) or: *You might not be able to restore from an image that on the drive being restored.
Copy the InstallESD.dmg file onto the USB drive (just copy, not burning etc).Assuming that the InstallESD.dmg is on the windows 7 computer:
