Lol, I finnaly got it down last night.
Run to the hash mark and be sure you do a running lob. "lets say from the left hash"
It will bank off the board to the other side of course.
Run to the opposite side of the hash to the top corner of the lane. "right side of the free throw line"
Hit the dunk button while going to the goal a little past it. "BOOM SHAKA LAKA"
Its actually pretty easy that way. I read that you can do it if you are alone on a fast break.
If you are playin 1on1 then you can do it every time on the CPU.
I myself need to quit rippen off the cpu.
When behind in a Game I always find myself standing sideways with my arms up while the cpu throws the ball in at the hash mark. Bounces off me rolling down the court . Grap it and slam it home.