or

the first joint is the 'root' at the wrist

if you have one finger working you can get them all to.

put the joints in the other fingers keeping that first joint the root joint (the skeleton of each finger should be connected to that first joint)

now shift select in the same way you did for one but do it for all of the, do not select the root joint.., should work..,

as has been mentioned.., probably better to use set driven key.., but this is a quick and dirty way to do it (my way that is, not the SDK)

i dont think this is a clear explanation so good luck