A fairly standard speed drill (boring, but very good):
Set up the OB near the side rail, 1 diamond from the corner and CB near the side pocket. Keep it simple and realistic... both balls a bit off the rail, and give yourself a slight angle towards the rail. Then try to sink the ball and draw back 1 diamond. Don't stop when you can park it near that diamond just once, repeat until you feel you have the diamond down cold... say 4 out of 5 times. Then move on to drawing 2 diamonds. How far you take it is up to you but I'd say at least repeat until you can draw to the side pocket four out of five.
Follow drill: same deal but back up the CB and OB 2 diamonds. Follow 1 diamond, 2 diamonds, etc. Try at least a couple parking the CB very close to the corner (don't try to scratch, angle yourself enough so that the CB can follow forward and rest on the end rail).
These are not original but they deal with shots that will come up over and over again. You are only dealing with certain distances (3 diamonds) but I find these distances are pretty common and are long enough that control becomes tricky, but not so long that it's asking too much.
This drill is more or less from Kinister though I'm sure others have thought of it.
Here's a position drill I came up with:
Set up a cut into the corner pocket where you'd usually play the shot to spin out 2 rails towards the middle of the table with outside english. I won't tell you where to set it up or what distance, just find a common and fairly easy cut that you like. Mark it with chalk/spit/donuts/whatever. Here you're controlling the angle more than the speed, because a smart angle will allow you to dog the speed a little and still come up ok.
Plant a piece of chalk right on the edge of the foot rail (so it's even hanging over the rail a hair, if necessary). Try to sink that ball and have the CB hit that chalk. You should see it pop up off the rail a bit. Repeat (using the same speed and tip placement) until you can hit that chalk consistently, and observe where the CB hits the 2nd rail. Now put the chalk on the 2nd rail and try to hit it on the 2nd rail. It's a little tougher so just try for 3 out of 5 or so. Once you have that 2 rail path burned into your brain, observe the line where the CB travels. Set a ball somewhere along that line, at least 2 feet from the side rail. Now try to make the CB run into that ball. Depending on the shot you set up and how well you're hitting 'em, either 2/5 or 3/5 is good enough.
Once you have that 2 rail position nailed you'll find that every cut starts to look a little like that 2 railer, and you'll find you can control similar cuts just as nicely. It gives you a good rock-steady reference point for this particular kind of shot, which may come up as much as 35 times in a single game of 9 ball