montage son au 1/100e sous FCP4 ?

La possibilité sous FCP4 de monter le son avec une précision supérieure à 25 i/s est évoquée dans le manuel (p.466), dans la notice de Peak ou dans des forums. Comment y accède-t-on concrêtement ? J'ai beau zoomer la forme d'onde dans le navigateur, ma tête de lecture continue de se déplacer d'une image (1/25e) et pas moins.
Quelqun sait-il y remédier ?
Ci-joint article anglais:
Sub-frame Audio Editing
Final Cut Pro gives you the ability to do sub-frame audio editing, that is, being able to effect an edit at a fraction of a second interval. In order to work at smaller than frame resolution, all you need to do is adjust the timeline magnification tool. By clicking and dragging to the left with the zoom tool, your playhead marker in the timeline in the Viewer will become a large black bar. This black bar covers the width of one frame and acts as a reminder that you are now editing in sub-frame mode or up to 1/100th of a video frame resolution. As you scrub the timeline magnifier tool left, notice how the playhead bar gets thicker and thicker? This is Final Cut's way of indicating that you are working at higher and higher resolution, allowing you to make very fine audio edits, cutting out small ticks, pops and breathes for dialogue editing or for smoothing rough audio edits.
MERCI.
Merci