Having done this exact thing I would recommend rigging the hand and then putting Set Driven Keys on the wrist joint or a hand control. This may take a long time to set up, but it provides better control that the other options.

With the SDK, you can fully set the hand for every possibility:

Bend on one finger
Bend on each finger
Create a fist
Point
Thumbs Up
Close fingers together
Spread fingers open
Rude Guestures
ect...
ect...

I recommend this set up rather than a fast easy approach and you'll learn something too