what I'd do using the software I have:
use SoundForge to record the DATs to a WAV file from your SPDIFs, creating markers based on threshold. Then use a batch macro in SoundForge to make selections based on the Markers and export these to separate WAV files with the Paste-to-New command. Then use a NT/Linux/whatever script to kick up the commandline-operated mp3 converter by Fraunhofer IIS (or any other commandline-based converter) to convert all of these separate WAVs to mp3s. This isn't really realtime, but can run in the background while you record new DATs to disc.
what time is it?
Its 15:09 here in central europe, daylight saving time...