I would do some searching over at MPH forums on this topic. IIRC its basic purpose to the provide better flow in the drivers side head. It does this by allowing coolant to flow by the #8 cylinder. Basically what you have to do is drill and tap a threaded insert on the unused water passage on the intake. If you look at the bottom of the intake and the top of the cylinder head you can see exactly where to drill (around the #8 cylinder). Once you get you fitting installed you run a line from there to the output on your heater core (you have to make a T connection).
Thats it in a nutshell. Like I said, search over at MPH- thats where the best info is on it. Also, take pictures and document it, then post back here so we can see how you did it!!!
Also, are you going to run a 160-180* t-stat and lower your fan turn on temps??
