If you have a box without a control panel and you have several IP addresses assigned to your server, here are some steps to add them into your network configuration.
# ifconfig
will output all the configured addresses. For example:
eth0: inet addr:10.10.10.10 Bcast:10.10.10.255 Mask:255.255.255.0
and more information.
To add on extra IP addresses type:
# ifconfig eth0:1 11.11.11.12 netmask 255.255.255.0
for additional IP addresses, make sure you increment the 1 in eth0:1, for example, a third IP address (third one including your BASE IP) would be added:
# ifconfig eth0:2 11.11.11.13 netmask 255.255.255.0
Hope it helps anyone struggling!