G Hub only let's you use the macro buttons on Logitech keyboards as triggers, so u can't assign macros or lua scripts to regular keys. It's possible to use modifiers as conditions, such as triggering the script with MMB only if lctrl is pressed, but not with lctrl alone.

This should be simple to do in Autohotkey, but some anti-cheats could flag that as irregular software interactions. Give it a try if that's not your case.