Apple Final Cut Pro 7 - Manual (Page 95)

Chapter 4 Working with the Canvas and Timeline 95
Place a clip so that it starts at a specific point in a sequence:
Place the playhead on a frame in the sequence where you would like to add a clip.
1
(Anywhere will do.)
Press I to set an In point for the sequence in the Timeline.
2
Sequence In point marking
where an incoming clip
should start
In the Viewer, set In and Out points in a clip that you want to place in the Timeline. 3
Drag the clip from the Viewer to the Overwrite section of the Canvas Edit Overlay 4
to place the clip at the sequence In point. The clip replaces the one in the Timeline
starting at the In point that you set.