If you can get the rotation and get a 4 on and your only problem is locking on, then I'd say just practice slowing down the rotation as much as you can to the point where you can control it well.
I got that down for mine so I'm pumped on it. Definitely one of my favorite rail tricks.
Also @vanular, HOW DO YOU NOLLIE LIP 4?? That is my dream trick and I've only seen you do it before. I got soft skis and I can lip 4 but every time I press my skis I lose my balance/ air composure and bail before I even get to 180. Also tried nollie lip 2 and caught tails trying to get that press in.