Sorry, I meant it can’t be done simply by the customer using harmony’s current activity paradigm. I have no idea what it would take for logitech to change the way they process button presses all together. My point was just that you can do it now, but it’s complicated to explain and clunky to use. 
As for questions about the piston, ask in the core peer assistance thread and people there will be glad to help you. That’s where the core experts hang out.