Anyone have an earth and animal-friendly way to get rid of mice?

I saw one walking out of our fireplace the other night, and the Pie saw one coming out of our hot water heater closet the night after that.

I have since vacuumed up everything, shoveled out the fireplace (which is blocked off and broken), and done my best to keep the house crumb-free.

We read that fabric softener dryer sheets were a good repellent.  The stronger the better.  I’ve jammed them into all the cracks I can find in the hopes they will do the trick.  The problem is that neither of us is used to strong perfumes anymore, so we’re wandering around sneezing our faces off.

I also heard that peppermint oil or tea tree oil rubbed onto surfaces they might pass by is also a good repellent, but I have so far been unable to locate any in St. John’s.

Steel wool or copper mesh is supposed to work well, too, but I don’t think I could jam it into those cracks without severing the tips of all my fingers.

My landlord has told me that she will call Orkin if necessary, but I’m not too keen on poison, both for my own cardio-pulmonary system and that of the poor little mice (it’s not their fault, they’re just following a biological imperative).  If I can keep them out until the spring, we should be okay.

Any ideas?