It's really difficult because the Computer (AI) knows the button combination you have pressed and knows you have attempted to dive, so 9 times out of 10 you will be caught, so what's the point in adding this feature? Just for show if you ask me?
But then again I'm thinking the master player could probably master the technique and you'd have to do it within a split second before the defender attempts to tackle the ball off you.
Personally, i've never tried it in online mode or in exhibition as there's too much going on, i'm usually too busy trying to nick a goal in the last minute, i'd rather go for goal than risk giving a free kick away in the last minute lol, if anyone can get it to work, that's amazing lol