The only way I can think of doing it is to use the Styling controls to divide one long section of hair into three strands ... in other words, grab the left third and move it out to the left, and then grab the right third and move it out toward the right. Then, grabbing one section at a time like you would in "real life", use the move tools and whatever else is needed to braid the hair as you would in real life. I would imagine it's very tricky, though. Not something I'd want to tackle. 8-)