There is a way to do this but it is not ideal for reasons I describe below.
Simply adjust the 'Duration' of the IR code. I believe that the 7000 had that feature added.
The issue you may find is that in cases where you need a quick-press vs a long-press, you may have to create 2 buttons and for the one you need the long press on, adjust the IR Code on that button to a longer 'Duration'.
F1 help in PPENG will likely give you some pointers.