You can remove the default route (optional).
su - root ifconfig eth0 192.168.1.69 netmask 255.255.255.0 up
SSH is normally open and running, but to be sure...
route -n | grep ^0.0.0.0 route del default gw 192.168.1.250
Use ping to verify physical connection to other machine.
service sshd restart service iptables stop
To set your IP configuration back to what it was originally:
Make sure you have a proper cross-over cable http://en.wikipedia.org/wiki/Ethernet_crossover_cable. If your systems are new, your NIC's could be auto-switching and apply an internal crossover when necessary, so you can even use a regular cable. Ethernet is low voltage, so you cannot damage anything.
service network restart