This uses a similar technique to a Frontside 180, although it may seem a little more tricky to begin with because you're turning blindside and you won't be able to see your landing until you've completed the trick.
Use your front shoulder to turn and your legs will follow. It's a bit of a weird one because you're going blindside, so you need be a bit confident with it.
You put your feet, basically, in the same position as you would an ollie, but with your back foot more towards your tail so you can scoop it round.
You do the Ollie, when you're nearly there, turn your shoulders and your body will start to turn round, and your legs will too.
Your legs will follow where your shoulders are going. When you're about to feel yourself come down, you turn your legs more and your shoulders more, and you'll do the full 180. When you land, try landing on your bolts and roll away backwards.