This is unfortunatley not possible, because when you render a montage with the batch processor, there are less options available than when you render from the Master Section dialog. More exactly, you can only render the montages as a single file, not as multiple files.
The only approaching solution I see would be this one:
- you render each audio montage as a big wave files with marked regions, using the batch processor. Each one in its own folder.
- you use the auto split clip (it has a batch mode), to split all these wav files in smaller wav files.
- you use the batch processor again, to convert all wav files into mp3 files.
That’s not so much work actually because each step #1 to #3 is a single big batch step.