I use the "Alton Brown" method, revised for the kettle or WSM. (i.e. Reverse Sear)
Cook at 200F until 118 IT, remove from heat wrap in foil and rest until IT hits 130.
While resting open the vents so your fire gets HOT. Once it hits 130 unwrap and throw back on the grill to sear the outside. Remove, rest and slice.
Gets you a nice med-rare all the way through with a nice crust.
I just did a small 3 lb'er last weekend.