If your ISP has provided you more then one IP then what you can do is go into the client configuration and click on the IP pool icon. Then assign add whatever IP you want them to have, after that you need to go to the domain you want to change and click the hosting icon. At the top you should now have a drop down menu where the IP address is and you can switch it to the new IP. This will auto correct the DNS as well.
Hope that is what you are looking for.
IC