Butterfly lighting comes from the shadow thats created under the nose. This happens when the lighting source is placed behind and above the camera. This is most often used in beauty shots, and leaves a slight shadow on the the neck.
This affect can also be simulated by placing a reflector below the chin. This can have the effect of emphasizing the check bone.
Position the light slightly above and behind the camera, if needed a reflector can be placed under your face to emphases your checks.