You will probably need somewhere between a 30 degree and 45 degree toe-in to achieve a crossing point of about 1.5' - 2' in front of the listener. Using the laser will help. The benefit of toeing in this dramatically is usually a wider sweet spot and less impact of side wall reflections. Of course the type of speaker will have some say in that.
Once set up a laser and some flat mirrors can help you identify the reflection points. If you want to look into this further go here:
http://www.decware.com/paper14.htm
