if it's IDE, just pop a standard IDE Device in it. I have had a few firewire cases (including a DVD-RW that died (sony) and popped various IDE Devices into it. It's all the same. All they are, are FW400->IDE Bridges. Nothing special. The only thing they really customize is the case and the drive in it perhaps. The board is just a Medium for the device and the Firewire out port. Go ahead. Just don't think it's hot-swappable though. You gotta power it down because it IS ide.

Good luck on your experiments!