would be correct. I just responded with a shot from the hip. Reading John B.s post on where the common lead connects it looks like it will be an under the hood job but the new common point must be located. I also have a new harness in my car and if the common point has been relocated then that's going to spoil the party until it can be located.
I really don't feel like delooming my new harness to find this point but I'll do some searching and see if I can locate it. Once it's located a simple relay would do the trick.