I know this sounds weird but you shouldn't try it until you know how to do it. I jumped all over a local photographer in my area when she posted her BTS shots of her doing that same pose with a newborn and literally trying to pose the baby like that without support. You can easily injury a newborn quite seriously if you do some of those poses incorrectly. Newborns aren't strong enough to hold a pose, and their neck muscles aren't strong enough to support their head yet. It could end very badly if it's not done correctly.
In my opinion the only way to be able to do that pose safely (THAT'S the key) is to composite the photo. Like zyndurai said, check youtube, you can find videos showing what shots you'll need in order to get the composite right. Then practice. Practice on a stuffed animal, or a doll. Practice setting up the shots, taking the shots, and making the composite afterwards. Once you're confident that you can do it successfuly, and SAFELY, then do it with a newborn. This is one reason I refuse to photograph newborns. It's risky, and the poses that some parents want (thanks to sites like Pintrest) can be flat out dangerous if tried to done with one shot.
I'm telling you, I lit up that photographer that did it here. She was one of those who "saw it on Pintrest" and tried to do it without knowing and understanding how to do it.