Set Parameter C128 to 1 (default is 2 for bootp, you should see it scroll across the screen for that).
make sure C129,C130,C131,C132 are set to your IP Address C129.C130.C131.C132 (set the IP on those parameters for each octet).
133,134,135,136 are the subnet
and 137,138,139,140 are the gateway. once those are set and you set C128 to 1, it should be using the set IP once it reboots