If you have a Midi bass track, you can use the piano roll:

http://youtu.be/V97VYOeotmk

If you are using a Bass realtrack, what you want is impossible within BIAB. I recommend you exporting your track to an external DAW and edit it there (most modern DAWS have powerful note stretching and pitch shifting audio tools these days)

Last edited by Cerio; 11/29/14 10:39 AM.
Latest BIAB version, latest build.