Where is your problem?
Resolve can output many audio tracks, so build timeline with 6 tracks, add audio for each 5.1 channel (I would use mono tracks not 5.1 track) and export ProRes MOV (export as many tracks not multichannel 1 track). You will end up video+6 mono tracks. Order is the same as in your timeline. You can add channels tags to MOV metadata with QT7 on Mac (or QT7 PRO on PC):
http://images.apple.com/my/itunes/lp-an ... ide5.2.pdf
Or you can simply put channels order in the file name or on slate in the master. I found this approach more reliable that using 5.1 tracks.