First of all, my rats completely freak out when I try to give them a bath. They just don't like water.
For anyone reading this, if you have more than one rat, definetly do it one at a time.
What you could do is get the water on luke warm, and get a dishclothe and wet it in the water. This is something you can hold your rat with.
Don't use soap. If you really have to, just use a tiny bit of mild hand soap, and wash it off completely when you're done. Don't wash their face or privates with soap. Of course you could do behind the ears.
Still, I wouldn't advise you to use soap.
Your ratty can dry themselves off. Give them a dry dishtowel to sit in after. This makes them feel secure.
Lila