you can make peds (who are on a bike) do whatever you want, cause they're kind of glued to the bike then.. if you push them off the road to a wall they'll even climb the wall..
however you need alot of luck to make a ped do a 100% flip
1. why the hell do you need a wallhack, you'll only see garbage and flipped poligons inside of the buildings (you'll see nothing but empty space)
2. we're already building in some prevention against cheating..