What's your goal? When I edit to music, I'll usually open up the clip in the viewer in FCP, and listen through the whole song, marking beats (offbeats, hits, w/e) with the "m" key. Not terribly elegant, but cheap and simple enough for most uses. Makes snapping edits to music very, very easy.
If you're trying to get the filters to work in time to the music (delays, phasers, filters, etc), use a metronome or something like
this to find the BPM and enter that into the project info.