Simple: turn the audio file into a video file (FLV).
There are probably much better ways of adding audio cue points that I haven't discovered yet, but Flash MX 2004 or Flash 8 don't seem to have any classes / components to help you do this quickly. Flash DOES have a selection of Media Components that allow you to add cue points to mpg or flv videos.
Simply convert the audio to FLV by exporting it with QuickTime Pro or another audio/video tool and the Flash Video Encoder (I use Sorenson Squeeze for this). The Flash 8 video encoder even allows you to add Event or Navigation cue points to the audio.
Import the FLV into your flash movie using the MediaDisplay component to add cue points as you would with video.
There's also a tutorial here that uses FlashAmp, the "Lite" version costs $45. This is probably better than my solution (but not as quick) as it can include the volume and spectral properties of the sound.