beg the profs who wrote them to send them to you... mine did that before she sent it in, actually..... it really just depends on how close you are to your lor writers... you couldn't 'officially' get the letters (at least not if you signed a waiver) any other way...
At this point, I don't really care. They must have been good enough if you're in medical school. Plus, if you are worried that they say something bad, then flat out ask them what your weaknesses are. Just relax and bask in the glow that you are going to medical school. 🙂