There are a few methodes you could try, to capture the movement of paw coming up to nose.
A piece of tape over the bridge of the nose, dogs hate sticky things on their nose, so they will try to wipe it off with the paw.
A 'scrunchie' ( elastic ring girls use in their hair ) , over the nose.
Blowing air on the nose works with some and not others.
This is defineatly a clicker trained trick, with the click being spot on timing, just before the paw touchs the nose.
Another thing which might work is, paw targeting , starting with dog in a drop, and your hand on the opposite side of the paw you want the dog to use. Ask for 'shake' or 'paw', then C & T.
Hope that helps.