If you know the MAC address you can assign an IP address as follows:
arp -s 192.168.2.20 00-20-4A-80-64-0B
(for windows systems)
with 192.168.2.20 being the IP address you want to
assign to the router and 00-20-4A-80-64-0B being the MAC address
The address that you assign needs to be in the same subnet as used by the address in your computer.
There is a 8.2.6.5 version of the 585v7 firmare.
Michael Chare