Coming in late on this: 

> Sounds good. Do you know of a way to obtain a MAC address without
> hooking up a keyboard and monitor or opening the box? The boxes
> are sealed by M&A and the warranty is voided if we open them.

I've been thinking about this for quite a while before (whithout doing
any coding so far, though).  My idea would be to power up the machines
one at a time for the inital setup period; this way, you'll always
know the MAC address of the board that just came up and can assign
anything you want to that at that time. 

No need to figure out anything externally.

Konrad