I buy live mice and prekill them (so they won't bite my snake) and she takes them just fine. I wouldn't waste time throwing live mice in a freezer because then you'd just have to thaw them out.

I'm sure lots of ppl on this site will tell you lots of ways to take care of the mouse, but here's what i prefer:

I kill the mouse RIGHT BEFORE I offer it to my bp, that way it's still warm (sounds gross I know). I prefer the "swift blow to the head" method over CO2, but you can be technical and put a pensil/screwdriver (etc) at the base of it's neck and swiftly pull the tail up and back (same time) to break it's neck. I just hit them in the head with a blunt object...they never feel a thing, know it's coming, or suffocate (as with CO2, though ppl say it puts them to sleep first).

I read that bps CAN NOT DIGEST COOKED FOOD. Aka if you're gonna get frozen mice, be sure when thawing that they don't get to too hot and start to cook. This is another reason I buy live and prekill.

Hope this helps and good luck!!!