You should forget about it. Arma 3's engine is hella complex to the point where I believe it would be super hard to create an aimbot (Don't quote me on that). AntiHacks are another large problem, it would most likely have to be an external program which would most likely be very extensive and difficult to write.
That being said, say you do get one coded I'm not even sure how you would get it past Anti-Hacks. It would most likely get detected eventually, especially if you were to hand it out.