First, start networking in BackTrack 4:
/etc/init.d/networking start
Next, set the static IP address:
ifconfig eth0 10.1.1.69 netmask 255.255.255.0 up
Next, set the default gateway:
route add default gw 10.1.1.1
Finally, set DNS servers and search suffixes:
nano /etc/resolv.conf
Add the following lines for your environment:
domain internaldomain.local
search internaldomain.local
nameserver 10.1.1.21
nameserver 10.1.1.21
Now you should have network connectivity with your desired static IP address in BackTrack 4.