I use a USB numeric keypad to jog my machine. It sucks that I have to go over and hit shift whenever I want to change my Z-axis.
Is it possible to get PgUp PgDn as alternate keys?
Check out SharpKeys. It is a small utility that lets you change key mappings in windows.
https://www.howtogeek.com/howto/windows-vista/map-any-key-to-any-key-on-windows-xp-vista/
I also use a wireless keypad for jogging. It seems that the keys on the wireless pad map to different keys than the keyboard, and I don’t even use the alt-key number pad on my laptop anyway. What I did was map the 9 on the keypad to shift, so I just hold down 9 and then up or down to jog the Z.
What would be really nice if there was a keyboard shortcut to change the jog increment!