I find that a shoulder width stance with feet forward works my outer sweep. When I point my feet outwards and keep them wider, I find it hits my hams more
I used to think if you put your heels together forming a V, that it would hit your outer sweep, but a buddy of mine has a degree in Physiology and he says it B.S.
just squat....all the way down, and all the way up. foot position is minimally involved in quad development, the only thing (as was said before) is that it will involve hams and glutes more or less depending on how you sit back or down.