Hmm. Yes, Brektzar's method should be the best (realistic) way to do it, playing with the FPS settings.
You could also fiddle around with the IPO curve itself and just scale down on the X axis (x is the time axis), but that would give you a sort of fast forward effect, it wouldn't be very real.
"Along with 'Antimatter,' and 'Dark Matter,' we've recently discovered the existence of 'Doesn't Matter,' which appears to have no effect on the universe whatsoever." -The 5th Wave