Sorry you aren't able to find what you need. Since there haven't been any helpful replies here yet, try emailing AMD customer care: http://emailcustomercare.amd.com/
Some creative modder on Xtremesystems forums and overclock.net has blended the more recent raid roms into older boards. I was able to flash my crossfire iv to a more recent version since Asus no longer cares to release updates. I would check there.