Thanks to everyone. Tapestop and any other Windows or VST stuff doesn't
work for me (as I said I am on MacOSX with Logic).

I didn't found any AudioUnit for the job, but thanks to you guys and
some additional googling I found a wonderful little app called
SoundHack.

http://www.soundhack.com/

It has a function called Varispeed which works great! Basically I just
bounced the piece of audio I wanted to speed up/down, open it in
SoundHack, Varispeed'ed it by Speed with a custom logarithmic function
and reimported the edited sound bit into Logic. Then a little bit of
xfade and that's it!

-zapro
aka unita_logica