Note: you may need to move the OB a bit closer to the pocket for the first shot otherwise it may be too thin.
OB should be placed between ~1cm off the rail up to 1-2 balls off the rail, depending on what you want to practice
Again, all drills are scalable for your difficulty. If these shots are too hard, move the CB closer to the OB
Rule of 3: If you fail 3 in a row, make it easier. If you succeed 3 in a time, make it harder.