Simply run the SQL installer again and create a new clustered SQL Instance. Note that the new instance will also need a new, unique IP address and a network name in addition to the disk resource. It works exactly the same as the first time, except shared components are already installed and will be skipped this time around.

I am assuming the disks are already set up as clustered disks. If not, you need to do that first so they are in the Available Storage group.