Alright go at a decent speed and go fakie. Set up as you would for a B/S Half-Cab But put your front foot where it should be for a Heelflip. Pop 180 and at the same time do the Heelflip. What I found out is that you can think only about doing a 90 b/s Heelflip and you will go around more and you can tic tack out. Its not a very hard trick if you know how to do a Heelflip and b/s half-cab really good. Spend about 3 hours on it and you should be getting it. Remember think 90 and you will turn more than you think. Thinking about doing a 180 is quite hard. But first do the 90 thinking then after you get that down think 180. 

Good Luck!