Here is a more fully commented version of the above:
Code:
modprobe usb-storage        ## Ensure the driver for the USB-stick is loaded
mkdir /tmp/usb              ## Create a directory for use as a mount-point
mount /dev/sda1 /tmp/usb    ## Mount/attach the USB-stick at /tmp/usb
mount mtd:mfg -t jffs2 /mfg ## Mount the manufacturing partition at /mfg
cp /mfg/mfg.dat /tmp/usb/   ## Copy mfg.dat to the USB-stick
umount /mfg                 ## Unmount/detach the manufacturing partition
umount /tmp/usb             ## Unmount/detach the USB-stick
sync                        ## Ensure data is written to the USB-stick before removal