In our SetTimeCtr_SV example we use one key ("select" input) to select up to 6 parameters (3 timers and 3 counters) - you can do the same here. Just one set of up/down keys and 1 select button.
If you have the HMI, it seems to make more sense to me to use the keypad to enter your values instead of up/down key. In this case, just use a function key (say F1) as the select key to select different parameters (show the chosen parameter on the LCD), then use the numeric keypad to enter the data.