Just drop them in. If you are holding them over the snake, both you and the snake are more likely to be bitten, because the mouse is frightened and stressed. They're much more calm with four feet on the floor. I put them in, close the tub enough that the mouse can't get back out, and just keep an eye on it. The worst bite I've encountered so far was just a very, very quick mouse... Miqula struck, and the mouse saw her coming. By the time the strike hit, she got it by the tail instead of the head as it was darting away - and very determinedly coiled it anyway! She got her mouse, but she got a few bites on her belly scaled in the process. Clean, and they healed fast.