If your frog is that small you're going to have to culture fruit flies. You would also want to seed your tank with springtails and isopods. With the pinheads and the fruit flies you would have a varied diet which is best for the frogs.
It's a really good idea. Thanks, Cheri. Our bumblebee toad is smaller than 2 cm herself, and is eating pinheads right now. Fruit flies will be a nice addition to her diet.