Here's most of the setup for this shot. I slide the cluster as far forward as I can in order to minimize the amount of follow needed on the cue ball. The 1, 2, and 3 balls are all frozen to each other.

The 1 and 2 balls are aligned to the short rail pocket point of the corner pocket to allow for throw.

I place the cue ball 3 ball widths out from the long rail, just behind the 3rd diamond, as shown in the first image. I aim >1/2 ball hit on the 1 ball, so I can be sure I hit it first, with max follow and a little right to throw the 3 in. You can hit this shot pretty softly and still get it to go.