I still haven't been able to get Kaede's special double assault to trigger at all - I don't understand why?
According to the friggin official skill list set in the game, all I have to do is press

,

A + E after the 2nd hit of the

p move. I even tried SCing it like Empyrian said, but no luck at all.
EDIT - I'm an idiot. Closer examination of the actual text says:
"Condition that must be fulfilled to perform the special double assault - the 2nd hit of his

p must be executed.
To cancel the condition by force, allow the 3rd hit of his

p to be executed"
So, for anyone else who's confused like me - you *need* to supercancel from the 2nd hit, then do the

AE command.