This one really is simple. You are going to make the 8 ball in the side pocket without touching the 9 ball! Get four balls; the cue ball, 9 ball, 8 ball and some other ball. The cue ball, 9 and 8 ball are all frozen. The cue and 9 ball are frozen at the middle diamond on the long rail. Use the forth ball to make the set up faster; put the 4th ball between the rail and the 8 ball - this way the spacing between the 8 and the rail is dead on. Once the 8 is set in place, remove the fourth ball from the table.
Aim the cue ball directly at the mid-point between the middle and third diamond on the long rail. In the diagram I've placed a piece of chalk at the aim point. Use a medium speed hit with a touch of left. I put the left on so that as my cue comes through the cue ball, my cue gets out of the way. This is a push shot, so don't get weirded out that the shot is so close to the rail! The reason the cue ball doesn't hit the 9 ball is because you are smushing (I know, that isn't a word) the cue ball into the rail (i.e.: rail compression) and it slides past the 9. If you miss the 8 ball to the right of the pocket (up table - as you're looking at the diagram), move your aim point a little to the right of the chalk. If you miss the 8 ball to the left of the side pocket, aim to the left of the chalk. I totally know that at first that seems backward.. but remember.. you are KICKING the 8 in, not banking it!!
Good luck and tell me how it works out for you!!