Apple Final Cut Pro 7 - Manual (Page 938)

3 Zoom in to the clip as far as possible.
When you’ve zoomed in
all the way, the playhead
in the Viewer is the width
of one video frame.
4 Hold down the Shift key as you drag the playhead to the exact place where the click
occurs.
5 Click the Level Keyframe button and reposition the playhead to place two keyframes at
the beginning of the click and two keyframes at the end of the click.
938 Chapter 57 Mixing Audio in the Timeline and Viewer