There is other software that can remap key combos, but I haven't tried it for the Windows key. It sounds like you want to use one hand to zoom in/out. If you can sacrifice a key closer to your number pad, you can remap one of those to be a 'Windows' key. If you have extra media keys on your keyboard, you can try to remap two on those to be zoom in/zoom out. Try googling for 'Windows key combination remap.' Best of luck.