Impossible so far as stated above unfortunately. There is payload's that spoof the firmware's revision higher or the pkg you may have seen recently (orbisman) and that's still in beta, it only changes the firmware number you see so to speak not actual modifications to the actual firmware on the system itself.
I'm hoping in the future that will spoof properly to allow higher firmware game's to be run on lower firmware but don't count on it!
I'm from the 360 scene (JTAG, rgh etc) and new to ps4 but I think personally with the ps3 scene being so big and the history of what happened with Sony and geohot, ps4 dev scene seems a bit skeptical. Correct me if I'm wrong. I'm thankful for what we already have! Dev's have worked hard to achieve what we already have! Can't thank them enough