I couldn't actually find a download for B-, and I'm too lazy to look for it on the vault, so I'll just type up some theoretical code that may or may not work.
In the EscapeAir Subaction
If IC Constant for Control Stick is Left
Momentum Set (Horizontal: a value, Vertical: a value)
Async Timer (1 to 2 frames before the animation ends)
Change Subaction: SpecialFall
End If
I don't know if you could just add another If over and over again until you have right, up, and down in there. But for safety, I'd just go with adding an "End if" and then copy pasting the code, changing it so that the control stick direction is different.
Again, this is all theoretical and I have no idea if it's possible to just add it with PSA and not with code in the gct.