Shooting uphill or downhill is the same. You need to figure how much HORIZONTAL distance you are shooting. So, hold your hand up in front of you at the angle you think you were shooting. If you imagine your hand being the long side of a triangle, you are actually shooting the distance of the bottom of the triangle(the horizontal distance), from the heel of your hand to a point directly below your fingertips. So, your bullet will act as if the shot is closer than it really is, hence, aim a little lower. It really shouldn't make too much difference at the range you are talking about, only a couple of inches with most big game calibers.
Thanx guys, it helped...last night I sighted my 30-06 in 0 at 200 and practiced a bit uphill. Found it was similar to my bow, but the distances are 10x.
This morning I was back after those boys in that clearcut, but got above them and this time when he bounced he did't get up. It was only 50 yards, downhill. A solid young fella with 3x3 (muley) headbones - my first deer ever with a rifle!! I'm hooked for life...