[audioboffin]

Create a stereo audio track. Drag each left and right file into the stereo track, use time stamping or positional markers to ensure the tracks line up L & R. Export out of the region list to generate stereo 16 bit 44.1 kHz files faster than real time, and drag the resultant stereo files into your burner app. Use something like iTunes to create mp3's if you want that process to occur faster than Protools can do it.