Detecting where PointingPosition exactely goes off-screen

[NoteToSelfFindGoodNickname]

In some Wii games, you move the Wiimote extremely down and then extremely up again to trigger a weapon reload.
I tried to detect such extreme ups and down with Unity-Wiimote.

I tried a lot, but in the end I wasn't successful. Movement can be so quick that it's impossible to detect any movement direction, so it isn't possible to say something like "If pointer moved upwards and is off-screen now, user made an extreme upwards movement".

Also, I didn't find any way to say from this code...

        float[] midpoint = GetIRMidpoint();
        if (midpoint[0] < 0 || midpoint[1] < 0)
        { 
            return new float[] { -1, -1 };
        }

... where exactely the Pointer is now (upwards off-screen or downwards off-sceen).

What would be the best way to detect such extreme positions?