X-Firewire Firmware Update Procedure
How to update the X-Firewire option card for Rosetta 200, Rosetta 800, AD-16x, DA-16x
This update MUST be done on OS X 10.6.7 (Snow Leopard) or earlier!!
If you try the update on 10.6.8 or later, then at some point your computer will crash:

In the example video below, the update is being performed on OS X 10.5.8 (Leopard).
The update files, and instructions User's Guide which include the firmware update steps, can be downloaded from the article for X-FireWire User's Guide, Documentation, & Downloads
For additional information on the x-Firewire card, see this article:
X-Firewire FAQ's