[Looburst]

This seems to be an ongoing question here, there is still no quick answer you're looking for. It simply takes time to be proficient at it. Forget the finger overlap method, do it right. You have to build up that muscle between your thumb and forefinger and the only way to do this is to keep at that F barre chord. Don't wuss out or look for other work arounds, just do it about 5 thousand times, then it'll be like nothin.