I compose quite a lot of music so my idea of interpretation is making a piece of music 'my own', while still sticking true to the composer. So, I don't really rehearse emotions, but when practising, I try to 'immerse' myself in the music and understand it as much as possible (both emotional and technically). Then, when I am performing, I play it the way that I would like it to sound, to represent 'me' almost. But, I always make sure that I am not deviating from what the composer originally intended.
Natalya
P.S. Oh, I was watching a program on the Leeds Piano Competition, and the Jury said that they were looking for a person who played their chosen concerto in a way that had a good interpretation, so was different and original, but still stayed true to the style.