Okay I whipped this up quick. There are some issues, though. The feet are sort of inside your pants, and when you are short you don't play walking animations and there are a few other quirks. Here is a pic of someone short standing next to someone normal:
Type /short to be short and type it again to be normal.
If any other scripters are reading this, please make this better if you can and want to. Even though it functions, it's only halfway to where it should be. However, I must ask that you
DO NOT POST THIS IN ADD-ONS unless you 100% fix it and make it bug-free.