Crucial SSD firmware upgrade -- usb flash drive issues

[Gary Aitken]

I've got a Crucial m4 SSD which needs a firmware upgrade.
>From the Crucial website I've downloaded an image which supposedly is an iso
image bootable from either CD or a usb stick.  

Since the fbsd install images are different for booting from cd and usb
flash drives (the flash image is significantly larger), 
I'm wondering if there's anything I need to be aware of when attempting this.

I tried copying the ssd firmware update image to a flash drive using:
  dd if=firmwareupdate.iso of=/dev/da0 bs=64k
which seemed to work.

However, when I attempt to boot the device, BIOS complains about it not
being bootable and says to fix it or select something else which is bootable.

I know the drive can be bootable because I used it for the fbsd 9.1 usb boot
image and it worked fine.

The documentation for the SSD firmware upgrade says "Create a Bootable USB Drive"
with the following steps (summarized here, no real content omitted):

  1.  Start with a newly formatted USB drive
  2.  Open a USB installer program.  If you don't have one, you may download
      a free one such as Universal USB Installer...
  3.  If you are using the Universal USB Installer, then:
  3a. At the Step 1 drop down box, scroll to the bottom and select
      the last option: Try Unlisted Linux ISO
  3b. Go to step 2 (in the pgm) and browse to the firmware ISO that you
      downloaded earlier
  3c. Go to step 3 (in the pgm) and select the flash drive on which you
      want to install the ISO
  3d. Click the Create button and click Format E:\Drive
  3e. A sequence of screens will appear and disappear...

The above is all highly confusing to me, as it's not clear who's doing what.
I'm guessing the "Universal Installer Program" actually writes a boot block
and then the bootable image someplace beyond that, and the iso image supplied
is not really a complete bootable image for a flash drive -- it's missing the
boot blocks.

Can anyone suggest a way to create a bootable flash drive using this image?