First off you can add multiple IP’s to each SliceHost VPS. Adding the secondary IP address to a SliceHost Virtual Private Server (VPS) is easy. Open the SliceManager control panel and click the Help tab to open a support ticket. In the ticket state that you want a secondary IP, the justification for it, and that you understand it will cost $2/month. Typically support responds very quickly and will configure the secondary IP address for you.
Typical justification would be that you are running a web server and need to have multiple SSL certificates.