Jon,
If all you have is the DVD and none of the underlying files, thats a bit of bitch. It will require ripping the DVD, demuxing the audio, converting to PAL, reauthoring, etc. etc., etc. And, it will certainly require outboard apps not in the FCP toolkit. If you’re still game I’m sure many here will give you tips about the apps they use for ripping etc., but perhaps you should consider capturing into FCP analog from a DVD player and then going from there.
DRW