Man, we need this on PS3I'm just going to assume that it is the same as normal vampire feeding was before since I havent played the DLC (I'm on PS3). So I'm gonna say sneak up on a sleeping person and crouch, then you can feed on them by activating them (kinda like pick-pocketing a sleeping person). I hope that helps
Unfortunately, the holiday will end, and we, the users of the PS3 will get back to our routine without playing Dawnguard^For realz? That's pretty cool