Need assistance with HotKeySet

I'm am trying to create a script that allows me to remap certain key presses. For instance an application I am using does not support shift modifiers as it is souly reserved for another purpose but some hot keys are not effected by the built in shift modifier so I would like to make hotkeys that use shift and perform useful actions for instance
Shift+Z is unusable but I would like to make it so that when Shift+Z is pressed it will send "j" instead. The other problem is that I want this to happen dynamically so I can't simply make a function that will send a j. Any suggestions?