Sometimes because of hills or hazards you really can't get into a normal Symple Swing stance. What to do?
The simplest thing to do is to set up the best you can bending your knees and setting up however you need to. Then you just "Freeze Your Knees". By that we mean don't change the bend in your knees on your backswing or downswing and until well after impact.
Keeping your lower body quiet will allow you to make a consistent, accurate swing at the ball whether you're on a hill or in a trap.
A note about hilly lies: Try to have your shoulders, parallel to the slope. This will make it easier for your swing to follow the slope rather than fighting it.