hiya,
have a look at the curve editor.
if you have set keyframes for start and end point you'll see it there along with the curve indication the current movement. if it's not there you can load it up with the stopwatch icon nect the the keyframe icon of the animated parameter.
then add new points (shift key) and distort the curve as needed.
check the manual for animating keyframes and the curve editor, there's tons of good info there.
hope that gets you started
++ christoph