Dk tankin is a fickle beast but its very simple to macro their rotation as it never really changes.

My dk tank uses a frost/blood sub spec that is rather strong, unholy works well but I don't prefer to use it as much as frost

The two things you need to be mindful of for dk tank is aoe vs single target as the threat Gen is vastly different and the rotation is completely trash if you try to run the aoe rotation vs a single target

When I get home I'll copy paste my tank macro for you on my cell at my parents right now with no access to wow lol