An S rank is earned by rescuing all Leedmees and collecting all five stars - when a Leedmee touches the star, it glows golden. While this may sound daunting, you can simply S rank the first stage five times. There's a few small changes, like the exit being on a head instead of a hand, but easily manageable. I've found the best way to do it is to get all the stars on the first ten Leedmees, then focus on not dropping any for the last ten.
As it stands, you do need a second person, as even the first stage requires enough moving around that a chair with a jacket won't cut it. Even then, I had issues with Kinect misreading me for a second and causing the arm to flail about. There is, therefore, a slight element of luck.
As far as advice, two i particular. First, make your movements steady. I've moved a little too fast and resulted in Leedmees flying over heads. You'll find the right speed before too long. Second, communication! Even if your partner knows what they're doing, it can't hurt to make sure. A little verbal direction will save a lot of frustration.