Hi Mike,
I recently purchased Synchron Strings and also want to use program changes instead of keyswitches.
I've set my first dimension to Pgm 10 and my second dimension to Pgm 20.
To select the first slot in the first dimension I created a program change event in Logic with a value of 10. I left the Bank field empty. (It appears as a minus sign.)
To select the second slot in the first dimension I created a program change event with a value of 11. And, so on.
Synchron will select slots in a dimension, sequentially, starting with the program number assigned to the dimension.
I did the same for the second dimension.
To select the first slot in the second dimension I created a program change event with a value of 20.
To select the second slot in the second dimension I created a program change event with a value of 21.
I'm not sure if this is the best way of doing it, but, so far, it seems to work fine.
I hope that helps.
All the very best,
Andrew