Just set your alarm clock to beep at 4:40 just like I did. Funny fact, yesterday I did that for new splash (2:55) and I didn't remember it BEEP'd that loud. I woke up making a jump and shouted "Oh my god Diablo III". And then went on Blizzard.com and refreshed 2-3 times before it appeared. I starred at it like 15 minutes and went back to bed, lol.
I'm going to attempt to stay up until 3 tonight, and then go to sleep for about two and a half hours and have mine wake me up at 5:30.