L.A.
Use regular ol' dandruff shampoo, the kind with pyrithione zinc in it. The cradle cap can actually appear anywhere on the body, and can look different, depending upon where on the body it is. This was recommended to me by my son's pediatrician. In fact, her started getting it on his body, and for quite a long time I used dandruff shampoo exclusively, both for his head and his body.
Good luck