I've been trying to find the answer on how this would work for the past few hours but there doesn't seem to be a concise answer on how to do it here. But alas, I think I might of found a way to do that very good looking "Power Post-Up" done by guys who are strong (such as Shaq, etc). I can also do it by will, so here we go...
First, you have to give it to someone who is strong. Though, you CAN do this with anyone, but if you do this to someone who isn't strong and against someone who IS strong, then you can go half-way on the animation only to find that your ball was bumped off your puny and weak body, so I suggest you give it to someone who is fairly proficient down low.
Another note is to have the player down in the post area. You can try doing this in the arc or 20 ft away from the basket and all you get is a whole lot of useless power spinning 20 ft away from the basket...
Ok, so if you got those two requirements checked, then we can try to do this maneuver to work. I would suggest that you first try this in either a 1 on 1 session or a pickup game in Play Now.
Once ingame, give to your big man down low. Don't even post up or back your defender just yet. Once you get the ball, press the hop-step. If you do this, you will notice that your guy will just take one power dribble to one side, then do a half spin and then end up facing the same direction you dribbled your ball while giving your dribble.
Now, press hop-step and when he's half-way done with the animation (meaning your guy took that power dribble and he's back is against the defender) quickly press UP on the left analog stick (not the freestyle stick). It should interrupt the rest of that animation making your guy "shoulder charge" your defender making more room for you. Be careful, using this all the time can land you in foul trouble so use it only when needed.
I hope this helps and I searched this forums for a couple of hours and I didn't find anything conclusive about this. If it's been posted then I'm sorry. Someone wanna test it out?