very difficult timestreching question

ok say i have a PHRASE sample(loop) i want to chop it very unevely based upon when notes are played within the sample. how do i timestrech from 001.01.72-002.01.48 to a certain bpm. i think you can only do this with recycle. ive tried streching the whole thing then chop. but if musicians are off i would rather strech each chopped portion. and this concept is not as necessary with drums because each drum doesnt play right up until the next drum sound starts, like a phrase sample.
the timestrech on the mpc only gives beat 1 is tightest it goes and that only allows for streching even zones. or the other timestrech option gives --100%through100% or something but that would be a guessing game.
any one have any hints on using recycle i heard it can find peaks then you can use midi and it will transfer the chop points into the sequencer of the mpc then you would load the sounds that have been chopped and streched with recycle.

you could do it with math if you were a total geinus. i dont know how, im retarded at math. but i know it's possible

http://mp3.deepsound.net/eng/samples_calculs.php

this should do you just fine