Similar to the idea of placing mouse bedding in the cage/tub...the technique I've used with success is this...

Take out a rat, place in in a tupperware filled with quite a bit of dirty mouse bedding (the dirtier the better!). Cover the rat in it, flip the container a couple times to make sure the rat is covered in the 'dust' of the mouse bedding. I usually leave them in the mouse bedding for 10-15 minutes just to make sure they smell more like a mouse and less like a rat. I then offer the prey with hemostats to ensure the scent doesn't get rubbed off or whatever.

I wouldn't do this though, unless the snake has a very good feeding response with the mice. If its somewhat of a problem feeder, stick with what it likes until that feeding response gets fully geared up.

Good luck.