I use a bunch of external USB hard drives for imaging at work, and I've finally figured out how to steamline the process.  Clonezilla is a great tool, but it gets annoying to go through the same exact steps when you are imaging 20 machines at a remote location.  If I had more bandwidth I would look into setting up a clonezilla server, but for right now doing a external USB hard disk to internal disk clone in 20 minutes works pretty good.

The key is to edit the /syslinux/syslinux.cfg file to setup a custom boot setting that sets all the questions that you normally get asked when you perform a restore.

  label Clonezilla Restore 740 Pub
  # MENU DEFAULT
  # MENU HIDE
  MENU LABEL Clonezilla Restore 740 Pub
  # MENU PASSWD
  kernel /live/vmlinuz
  append initrd=/live/initrd.img boot=live config  noswap nolocales edd=on nomodeset noprompt ocs_live_run="ocs-sr -g auto -e1 auto -e2 -c -r -j2 -k -p poweroff restoredisk ask_user sda" ocs_live_extra_param="" ocs_live_keymap="NONE" ocs_live_batch="no" ocs_lang="" vga=788 ip=frommedia  nosplash ocs_prerun="mount /dev/sdb2 /mnt" ocs_prerun1="mount --bind /mnt/LARL-740 /home/partimag/"
  TEXT HELP
  * Image machine with latest 740 Hubpub image
  * Warning, this will overwrite the disk.
  ENDTEXT