Its extremely easy: connect display to rig, right click on network icon in taskbar, set your connection to static ip.
Easy? Finding the keyboard and monitor is easy? Ohh and the mouse too!? C'mooon... and most likely those settings are also reseted upon reboot just like modifications in interfaces
Easier way.. Write script to modify /etc/network/interfaces upon boot and reboot network after making changes. No freaking monitors or mouses needed - only ssh access
/etc/network/interfaces
iface eth0 inet static
address xxx.xxx.xxx.xxx
netmask xxx.xxx.xxx.xxx
gateway xxx.xxx.xxx.xxx
Easiest way... Set static IP from router according to MAC address