You should always supervise when you feed live, you don't want the mouse to attack the snake and hurt it.

Also, any petsmart or petco has frozen mice and rats so unless you live WAY out in the boonies you should have one within driving distance. I find that my snake has a much easier time eating the petco mice since they're packaged differently and thaw out nice and straight. She eats those in about 5 minutes tops. I have seen her take over a 30 minutes for one that she tried to eat tail first and one of the legs was sticking out and she just had to crush the leg in with her mouth finally...