How to jump cast easier?

Other than what's suggested like using G5 keyboard's macro function, or using key mappers/tweakers which I doubt will allow you to input two keys on on button, you're out of luck. You probably have to write your own program/emulation for this since it's rather unique to specific usage. Plus I bet the existing remappers will make it override in the registry or global setting so when you're not playing maple, your keys are going to be messed up, just easier finding other alternatives or using those already suggested.