Haha, it's possible... Maybe thats why I never came across it? Then again I don't think I really tried to hard to figure it out. I know old games it had to do with storing finishers or something? Don't remember..
I am usually drunk when I post here. Forgive me if I don't follow up, I'm probably sober..
You don't have to hold RB to actually DO the finisher - just hold RB when you press up on the D-Pad (You will see your character do the opponents Wake Up Taunt) from there just get them in the right position and do the move as usual.