Not mice related, but a really good one for snakes that I've been using for a few summers is moth-crystals and ordinary garden sulpher, both mixed together. Snakes work off their sense of smell mostly and when they get near this stuff, it scrambles the signals and they won't go near it. We used to have Blacks Racers come into the garage pretty often as well as timber rattlers every now and then. Usually in the Fall when they were looking for a den spot. This stuff has stopped it dead. I just keep some at both ends of the garage door where there's a small space they get in. I would fix the holes, but then it'd screw with the motion sensors on the garage door. Not sure if it'd work on mice, but thought I'd throw that in there.
Just half and half of moth-crystals and ordinary sulpher you buy in the garden section. The sulpher is used to adjust the ph in your soil. The moth crystals either come in the ball size or the crushed type. If you can't find the crushed type, just put it in a bucket and turn it into crystals with a hammer or piece of steel. Great stuff.
HH
or 
