Here's how I hit these shots and I have to hit a lot of them living in North Georgia. Note that I always try to 'swing along the lines of my body.'
Ball Above Feet = Clubface Right of the Target, Body Left of the Target
Ball Below Feet = Clubface left of Target, Body Right of Target.
Downhill lie = Shoulders parallel to ground, Ball position more towards back foot, 'swing right.'
Uphill Lie = Don't bother with shoulders (they are usually tilted upward anyway), Ball position towards front foot, 'swing left.'
Downhill shots tend to fade, uphill shots tend to draw. But if I want to hit them straight, this is what I do and it took a lot of experimenting to figure this out. Yesterday I had 200 yards into a green with the ball above my feet, almost at knee level and I hit a 3-hybrid to 10 feet.
With ball position, I've always lived by the general rule that you play the ball more towards the 'higher foot.' So with uphill lies the 'higher foot' is the front foot and with downhill lies it's the back foot.
3JACK