If you are using the Flunk version fo ANH for the basis of the edit then use the audio from that as a sync track. If you are editing video then you should really use the original audio track locked to the video track so any splices you make the tracks will still be locked and synced together which will make it easier in the long run to sync your new audio track.

Put the original audio track as your first track, which will be muted when rendering the 5.1. For your second track place the centre channel of the laserdisc 5.1. This way you can compare your sync track with this one. Don't adjust the centre channel to sync just yet though. Import the other 5 tracks of your 5.1 mix (1 disc at a time). Line all the beginning of your 5.1 tracks of disc 1 up and highlight each one. Right click on any one of the highlighted tracks and select "group>create new" (or you can just press "G" but this way you know its grouped them.) now these tracks are locked together. Do the same for discs 2 then 3. Now in the Options menu make sure that both "quantize to frames" & "enable snapping" are deselected. this will enable you to get a more accurate line up when syncing to the sync track. Now all you need to do is line up the centre channel of the 5.1 with the sync track. Just zoom in on the tracks so you can see just a few frames in view and then pick a section close to the beginning (the main theme is a good start) and line up the waveforms to match. Now you will either have to make some cuts or slightly change the length of each section to get this synced up. Someone posted a list of the reel changes somewhere in the forums so these would be good places to make the first cuts. Where you need to replace gaps at the end of each disc then use the 2004 mix. You will only need to use a few frames from this mix to patch it up so any differences in the mix will not be noticeable especially if you blend together each tracks by a few frames at least.

Hope this helps