I've always heard that Palmolive dish soap works.
Another thing is that Revolution is supposed to have one for puppies under 12 weeks.
Last, but not least, spray a towel with Frontline, then wrap the baby in it for a minute. The dead fleas will come off with the towel. You can also wash them with a washcloth dipped in 1/2 listerine, and 1/2 water. Leave damp for a few minutes, then dry with a cloth.
All of this for those darned fleas!