cd /etc/sysconfig/network-scripts/
cat ifcfg-eth0
Then copy the contents of this file onto a notepad
Change the IP in the copied text to the IP that you wantpico ifcfg-eth0:x
where x is the device number
Then copy what you have on the notepad to this file.
Then command the following:
ifup ifcfg-eth0:x
where x is the device number