Unlike the sumo deadlift where the feet tend to rotate outwards in excess of 45 degrees, the squat-stance deadlift requires you to keep the feet relatively straight. This position will produce the greatest strength increases.
Use a position that's anywhere between a normal squat stance (approximately shoulder width), to roughly 20% wider than normal squat stance. This means the feet will be anywhere from 2-3 feet apart when measuring from the outside of the feet.
Similar to a sumo deadlift, the arms and grip should be placed in between the legs to create a feeling of straddling the barbell. It should feel as though the bar is positioned between the feet and legs rather than in front of them. With this in mind, the grip will be anywhere from roughly 1-2 feet apart. The key is making sure the arms can fit between the legs without running into the knees.
Your lower body mechanics will be nearly identical to a low-bar squat. Focus on pushing the knees out and keeping the hips pushed back as far as possible while still keeping the chest up. Keep a natural, not excessive, arch throughout the spine while and keep your head in a neutral position.
Your torso will be bent over to approximately 45 degrees, which maximizes your ability to cock the hips back fully at the bottom (hip flexion) while minimizing sheer stress on the spine. This ideal position can't be duplicated with either the sumo or conventional pull.
After pre-loading the musculature by pulling slack out of the bar, focus on locking the spine tightly into position by squeezing the daylights out of your lats.