Before trying this trick, you should be able to F/S tail slide pretty well.
Come up to your target with a fair amount of speed and at an angle of around 45 degrees or less. Pop a Fakie Ollie and then twist your body and board to land on a tail slide. It is very important when you are popping down that you are thinking of how your weight should be spread out when you land. This is because most of the time you will try this you will lean forward too much and slip out when you land on your tail slide. Ok now you can get on, once you land put all your weight on your tail (it should be already there, you should have moved it there in the air). Slide across your target and then just do a simple twist out.