This page described how to assign a custom MAC address for the Modtronix SBC66EC and SBC66ECL boards.
Connect the target board to your network via it's Ethernet Network connector.
Supply a 7V to 24V supply to the target board.
Open a browser, enter following address: **
This should load target's web interface.
Click on the “Network Configuration” menu item. The default username and password is “admin” and “microchip”
In the “Network Configuration” page, enter the new MAC address. Click on “Save Config” when done.