Ok, I’m 99% of the way there and I just need a little push over the finish line! 
I have created a counter that tracks the game clock, and can be adjusted both forwards and backwards in 15 minute increments, via assemblage of a few Trigger Actions and Dynamic Properties - thank you to DrNostromo and his excellent example module.
The final step is to get the Turn Counter to fire a key combo each time it is incremented/decremented. That way the user will first set the game clock, and then all subsequent turn changes will adjust the clock automatically.
I am using the Turn Counter and have added a (Turn) Counter, but I see no way to make it send out global key commands? 