I actually warm a bowl of water and then dump the mouse in for a couple of minutes. If the mouse isn't warm enough, she won't eat it. She's struck at it, held it for a while, but after looking again in a couple of minutes, the mouse is on the floor.

If that happens, I reheat the bowl of water, dump the mouse in, and dangle it in front of her again, which then causes her to eat properly.

The biggest downfall of this is that the mouse can get mushy and sometimes can get really sloppy @_@ It does save on having to use plastic bags though