How to add additional IP to Xen VPS via SSH?

First, cp /etc/sysconfig/network-scripts/ifcfg-eth0  /etc/sysconfig/network-scripts/ifcfg-eth0:1

Then vi /etc/sysconfig/network-scripts/ifcfg-eth0:1

Change DEVICE=eth0 to DEVICE=eth0:1 

and 

Change IPADDR=the.old.ip.address to IPADDR=the.NEW.ip.address

Save the config file, then run command service network restart 

Done, the new ip address should pingable now!