Hitting off a sloped lie isn't as difficult as it looks. In this case, since I have a downhill lie, the proper way to tackle this shot is to allow nature to take its course. The slope makes me feel as though my weight is mostly on my forward foot (see below), but you don't want to exaggerate your weight distribution. It's also critical to make sure you level your shoulders and body to the slope as to assume your setup position. If you try to swing with your normal stance, you'll either make fat or thin contact and will probably lose your balance through the swing. Instead, take the time to adjust to the slope, and trace the ground with your practice swings to ingrain the proper feel.
Let gravity help you get in the right position on sloped shots. Any forced position will produce a poor result.