What's so difficult about it? You have five tracks laid out, and edit accordingly - in fact, you can group them all together so that fades are done on all tracks simultaneously (and it's easy to ungroup a particular track for a particular fade, and then regroup.) In fact, it's not a bad idea to edit with the 2.0 track first (to figure out how the video will go), and then go back and align the 5.1 soundtrack to the 2.0. You can line them up visually by looking at the waveforms.
What's so difficult about it? You have five tracks laid out, and edit accordingly - in fact, you can group them all together so that fades are done on all tracks simultaneously (and it's easy to ungroup a particular track for a particular fade, and then regroup.) In fact, it's not a bad idea to edit with the 2.0 track first (to figure out how the video will go), and then go back and align the 5.1 soundtrack to the 2.0. You can line them up visually by looking at the waveforms.