Best way to update cPanel main IP

We have had this particular server running for quite some time without any issues until today. We were just informed that we were the target of a DDOS attack and as a result, the datacenter has null routed the IP address in question. This IP address was not only our main IP address, but also the main shared IP for the shared hosting accounts.

If we were to pick another IP address in our pool to act as both the main IP and the new shared IP (Or split them up even), what would be the best way to change this in cPanel? I know we can set the new shared IP in the basic setup area in WHM, but I'm not sure how to tell cPanel to use a different IP as its "main" IP.