Micrologix850 and Panelview 800

Hello, I am currently trying to figure out how to make two of the F1-F4 function keys on my HMI scroll from push button to push button. I am doing this in case the screen ends up going out, in which you would still be able to operate with only the function keys. Any suggestions?

Use F1 and F4 to increment/decrement a register DINT_Temp in the PLC
Place a new indicator near each button that will illuminate based on a different DINT_Temp value
Use plc logic to OR the existing touchscreen PB with EQU DINT_Temp value and F2 key
Use plc logic to reset DINT_Temp back to 1 on screen change so it won't get lost as well as if it goes too high or low
Most importantly: place sticker on touchscreen telling operators not to use anything but fingers...

Thank you very much, that was very helpful.