Stub What would be the point? You might just fool your teacher, but you won't fool yourself. You really do need a night's sleep to consolidate memory. Several nights of sleep, even better--as you already know.
bSharp +1 - I don't see the purpose of cramming anything in a day, especially piano and diploma level pieces. Why not tell the teacher you didn't start looking at it until a few hours ago?
I know that many people can do this. My piano teacher talked about cramming entire Liszt pieces in 3-4 days, or shorter Liszt pieces like those from his Pilgrimages in hours. We don't always have the luxury of time, and so it's very important to learn to do this IMO. I can not imagine a high level professional pianist not having this ability.
Even now, I'm pushed up against my limit pretty often. I will tell my teacher that I managed to practice a piece for 6 hours on a given week, and he will ask me why I haven't made considerably more progress: that with 6 hours of practice, he would expect a page of music to be learned pretty well. So this question is important to me. I know that there is something really inefficient about the way I'm practicing and learning piano, and it needs to be fixed.