I don't really agree with all the previous advices.
I think shoulder width is fine. Lower the weight slightly more towards the stomach, but that will be the natural path as well, so as you put more weight on, that's how you will put up the lift.
Load up weight on the bar, as this excersise should IMO be heavy.
Keep it fairly low reps - heavy weight.
I dunno your normal rep range, but 5-8 reps would be a good idea.
YIP
Zack