Dialing in Cleat Position?

Is there a good way to determine cleat position on a new cleat/shoe combination? I hurt my knee yesterday after a week of trying to get a perfect position on my new shoes. I know there’s a “sweet spot” for the cleat (above the metatarsul?), but how do you find that, and how do you account for Q factor, foot angle (SPD-SL, only 6 degree of float), etc?

Have you seen this article http://www.slowtwitch.com/mainheadings/techctr/maintenance/cleat_mount.html ?

Some consider bisecting the head of the first or second metatarsal to be an old school method and now prefer to bisect the whole of the forefoot but for many people this results in a cleat alignment that could be as much as 5-6mm behind the ball of the foot. Athletes with calf or Achilles tendon pain should always check cleat position as a forward cleat position places additional stress and fatigue on the calf and AT. Poor cleat position can also result in running injuries such as fatiguing of the calves/ATs and/or tendonitis during runs as a consequence of a forward cleat position.