It’s quite straight forward. You need to embed the midi commands in ST3. I also send Program changes to my Xair mixer (channel 1). The POD is in ch 5, here I set the POD to preset 18 and then snapshot 2 (C69.1).
[midi@00:01.0: PC18@5]
[midi@00:02.00: CC69.1@5]
[midi@00:03.00: PC52@1]