You do realise, I hope, that content-wise it is very unlikely that the theatrical DTS 5.1 mixes contain any significant differences from what is on the SE laserdiscs. The sound quality could well be superior to 384 kbps ac3, but the only thing truly different about them is that the LFE information will be stored in the surround channels, intended to be low-pass filtered out to the subwoofers, since bandwidth concerns prevent the bass from having its own channel. There may also be some phase differences because of things like that, but only insofar as to be made optimal for the format.

Theatrical DTS is a different codec from the home video version anyway, so even if the timecodes could be read properly, putting it through your receiver or a software decoder wouldn't do any good.