|I don't have an old 2600 around to check on but if that command isn't supported, it isn't supported and you'll have to find another way. Likely you'll have to use another device. A SOHO router would work, and then you could plug that into your 2600 and statically assign an IP to 0/0 that is in the same subnet as the router's LAN side.|
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.