Hi again MacandSneeze,
I just ran a test using QuickTime Pro (version 7.6.6). As I thought, it is quite easy to split the audio into segments, using Edit>Trim to Selection.
There may be more efficient ways to do this, but I started by opening the music track in QT Pro, then dragging the markers into the appropriate position to highlight the desired section, then going to the Menu item Edit>Trim to Selection. Save and name that piece appropriately.
Open the original music track again, and drag the markers to your next section, then go through the same steps as above. You need to do this for each section you want to use in iMovie.
I just split a song (Something Stupid would you believe!) into 3 segments using the above method. The first segment was 30 seconds, then one minute, and finally one minute 4 seconds - making a total length of 2 minutes 34 seconds (the original song length).
As I said, there are probably better ways of doing all this. I was hoping to be able to simply split the track into 3 segments in one go. There is probably a Help item that explains how to do this, but I didn't bother to look it up, as I achieved the desired result using my own method 🙂
John