What are you talking about? Aim your crosshair/middle of your screen at whatever you want to hit, be close enough to it, swing. It'd be disastrous if it ever went the route of MMOs and let you just select a target and hit number keys which would land attack whether they are in front of you or close enough or anything else related to ACTUALLY hitting stuff. -.-
i don't know what makes you think it will be anything like that.
todd howard said all it is is your attacks gravitate towards hostile targets so you don't hit allies.
its not going to be an auto targeting system by any means.