I've never had to do this but I've talked to people that have and here is what I've picked up.
Look up how to tie a surgeons knot. Use unwaxed dental floss tie it off a little ways down from the belly. I'd say the distance of the width of a finger..then just clip below it..
You will want to get food in him asap since that animal didn't have the yolk to see it through its first shed..