I would think that in theory it would be better to put chains on the rear tires when driving downhill as one wouldn't want the back end to get in front of the front end. In the past I've put one chain on the front and one on the rear on opposing sides (left front/ right rear for example), but that was on an older 3/4 ton pick-up truck that didn't have all the fancy electronic stuff.
Either way, going slow, not doing anything abrupt and not braking while turning a corner will go a long way as well.