If you have a roller door/straight wall/fence etc - before you change your headlights pull up to it and look at the positions the beams are.
After you have swapped the head lights over - do the same and adjust them so the beams are in the same spots. My guess is they will be pretty close anyway 
Hasn't failed me yet!
Hot Red VX SS - 5.7L Gen3, Pacemaker tri-y's, Dual 2.5", 6 Speed, 3.47 LSD, 18" HSV Clubsport wheels
Stereo - Alpine 9887, JL 300/2, Audison LRx1.1k, Image Dynamics IDMAX 12", Focal 165VR's + Dynamat