If you are going to do a lot, I suggest getting a fluid bed. you can either make one, ( which has gone into depth in earlier posts) or you can buy one from Component Systems for $80. I have the one from component systems, I can crank out about 400 spinnerbait heads in an hour, just using that and a propane torch.
I heat up the head for a few seconds, and dip, the powder is nice and fluffy all of the time, and it leaves a very consistant coating, as long as you heat the heads up consistantly... I count to myself to keep them at roughly the same temp.
If you are only doing a few, you can dip them in a freshly stirred jar of powder, or, you can sprinkle it on... these are not the most consistant ways of doing it, and you wil have some disappointments.
Good luck!
Chris