neverblog.net

So, it’s technically possible to change a short name in OS X using the Apple-endorsed procedure listed on Apple’s site, but that method involves doing some really horrible things to your computer, since you’re basically using the BSD subsystem to trick OS X into thinking you’re the same person you were while actually creating a ‘new’ account.
Poking around on the web yielded this nifty tool, however, that seems to make renaming your account a snap. You can download it here, then check out the documentation at this website.
It doesn’t seem to work any differently than would the sketchy and complicated solution offered by the nice folks at Apple, but it does it automatically, so you can screw your computer up at the speed its processor runs, not just as fast as you can type. Good luck!