I don't think you can, a wav file is already audio. You can do it with midi. Or a time stretching program, but you can't change it too much before it starts sounding crappy.
A stop watch. Count the beats in 6 seconds, multiply by 10. In nuendo, there is a thing that you tap and it calculates the bpm, maybe there is something like that.
You can slow one down about 5% before it gets noticeably bad. You can speed one up about 10% before it gets goofy. This is assuming you're keeping the pitch the same. If you don't mind pitch changes, you can speed it up as much as you want...chipmunky.