I agree with the method described by Shiu. The only thing I would add is that this method would work best if you created the realistic hand with minimal foreshortening and with the view almost "straight on" - and the fingers outstretched. Since the fingers will be bending - they may need to be separated into 2 or 3 joint segments.
This way you can use finger movement and rotation, scaling, and skewing on both the palm and the fingers, individually - changing "Draw Order" for overlapping fingers - thus producing the illusion of many angles.
You will still need a lot of in-betweens - but, at least you don't have to draw them one by one. A lot of time will still be saved.
Greg Smith