Try scenting first. Keep a live mouse around for a while and scent with the live mouses bedding.
or you could try
I had a friend with a Burmese Python that refused to eat anything but jumbo live rats. He had to feed six jumbo rats every couple weeks just to keep the snakes weight up so this is what he did. He cut the hide off of a frozen thawed rat and draped it (stuck it) to the back of a very young rabbit. He did this several times and each time putting a smaller hide on the baby bunny. Once he got the snake to take a bunny without a rat skin, he started slowly sizing the rabbits up. The snake now eats rabbits no problem. He will only take them live tho. You could try the same trick with a mouse hide on a baby rat about the same size as a mouse?
I would never want a mouser. Expensive and I dislike mice very much. All of my balls only get rats, straight out of the eggs.