In a Telnet session, as previously discussed:
Run the following command, replace xx's with desired mac address value.

/usr/local/bin/macaddr 00:90:7E:3A:12:5C


If I am not mistaken, based on the mac vender identifier on my unit (VETRONIX CORP)... Then these would be acceptable value ranges: 00:90:7E:00:00:00 - 00:90:7E:FF:FF:FF