So there are three variables in your control here: aim, speed, and english.
Because the CB and the 8 are frozen, the CB will come off the 8 and hit the far rail in almost the same place every shot, even as you change your aim. This means a certain english is needed to get the CB to bank back toward the side pocket. Find that english.
A certain speed is needed so that the CB makes it back, but slow enough that the 8 has almost stopped in front of the pocket by the time the CB gets there (if the 8 is moving quickly, consistency will be very difficult to achieve). So find that speed.
Now that you know what english and speed you have to use to get the CB to do that right thing, change your aim until the 8 rolls up and almost stops in front of the pocket. Aiming further uptable makes the 8 roll faster, aiming more directly across the table makes the 8 roll slower. Once you've experimented enough to pin down all three variables, I bet you can make it very consistently.
-Andrew