Here's Chris A doing one on the WSM http://virtualweberbullet.com/porkloin1.html
You can go indirect on the kettle at medium heat cooking to 140 in the center then resting tented with foil. Temp will rise some during resting. You can also sear both sides for a few minutes before moving to indirect. Marinating will add flavor, but isn't required. Brining helps with moisture retention, but again is optional