thanks for your reply.

So do I get you right in that you want to map the modifier toggle 
actions in a different place than the virtual keyboard? (directly 
assigning modifier toggling actions to buttons of your remote when 
activating the virtual keyboard is already possible)

Or do you want to just have the modifiers being pressed for the 
duration of the button press itself?

Keystroke actors have not been designed for using them to press just 
the modifier keys, btw, so this approach will not work here. They 
currently will always also emulate a regular keypress with them. I'll 
see what can be done for the next version, though.

Best regards, 
Felix