In case you haven't played a lot of shuffleboard and don't know what a hanger is, Its when a portion of the puck is hanging of the back (it must be the back not the sides) of the surface. It's worth 5 points in the game as well.
The explanation to do it is fairly self explanatory. You just got to find that sweet spot with your swipe. The perfect swing, not to hard not to soft, perfect english as it were. It really wasn't that hard once i decided to dedicate time to it, and that's the only tip i have for you. Just dedicate play time to that achievement so you can fine tune your swipe. Oh, and just remove pucks from the playing field if it gets to crowded. No sense wasting that money throw if a guard knocks it off the board.
Edit: I appear to stand corrected. It is worth 4 points. I must have spaced on the value as 5 is how i used to play in my buddies basement. Thanks guys.