Yeah, just dig for the finger or joint you need:
The second example in the nuget paints squares on all fingers, but you can of course filter for the one you want. Each hand has 21 including the wrist.
I did this for Genuary yesterday and it is really cool:
What I found is, that one needs to have a bright room for it to be fast. Low light needed much more detection time while a bright scene was up to 5 times faster.
Also a cleaner image seems to detect faster, my GFs webcam is very noisy and that was slower and more jittery.
I drew points between the joints for visualisation first, then used them as emitters: