I have no clue!
I usually just kind of set and forget, and never have really fussed with PC messages with any MIDI stuff.
But I can give it a try when I get home. For you!
Gonna be a little while unless someone else more experienced has the time.
Update:
@Digino Yes it can for sure. I can send PC messages from both an instrument track as MIDI, and the dedicated MIDI track when I have either set to the matching auto channel of my Syntakt. Changing the program value on the OP-XY makes the Syntakt select the appropriate pattern on transport play.
I’ll reiterate that I don’t have much experience with PC messaging other than flipping through presets of an external synth being controlled by my Syntakt, so I can’t confirm how to do exactly what you seek to accomplish.
So I was rearranging my desk again and put the Roland A-49 back on the table with the Syntakt and OP-XY. Turns out just having a normal-ass keyboard controller running the two together solves my one gripe pairing them!
The MIDI goes: A-49 → OP-XY → ST
Now I can play whatever active track on the OP-XY, and if the active track is MIDI it plays my ST. Notes C0-B0 hit each ST track like a drum trig. Step components, players, all that affect the ST!
Already working a project where the first two OP-XY tracks are drum and melodic Syntakt parts.
This is super rad! The OP-XY synth drum I wanted was my Syntakt all along.
AND I CAN D-BEAM AGAIN!
can’t wait to get home and try this!!! With the 8 individual out I’m going to lock into a minimal techno mind meld. 
