It can't be that hard.....I mean, someone made a Phantom Hourglass hack to make the touch screen movement work with the DPad. That couldn't have been easy compared to this.
Then again, one, I know absolutely nothing about hacking so what do I know, and two, pretty much every hack here is just a story change which just means remapping, and I guess this does go beyond that. Maybe the PH guy was just really good.