There are two parts to getting rid of this chronic problem.
1) Do your darndest best to hit pitch shots about 30 degrees to the right of your target. In other words, hit push shots while you are set up to hit the ball straight.
2) When #1 can be accomplished with a fair bit of consistency, learn to swivel or roll the left forearm in conjunction with #1 until dead straight or draw shots are achieved.
Ok. This is an interesting drill. Your going to think I am dumb with this question though.
Do you try and hit it 30* right by changing the angle of attack? Or by holding the clubface open? The first would make more sense to me as it would be teaching the hitters angle of attack. But I could see some value in the other as it would teach you to feel various clubface manipulations.