Most dedicated servers come with 8 'subnetted' IP's allowing for 5 usable IP's once you have used 3 for gateway, broadcast etc. Who is your provider? If your using any decent control panel you can do this via the web interface.
██ | BlueWave Communications Ltd - The Island's Communications Provider
██ | URL: http://www.bwc.im/AS: 201898
██ | Jersey | Guernsey | Isle of Man