I found some VST plugins that can do side-chain compression in Premiere Pro CC.
It works by placing the plugin on both the music and the narrator. This is available since quite some time but these are free non professional plugins.
Of course doing a roundtrip in audition this works wonderfully with Fabfilter plugins.
But not everytime a roundtrip is worth the effort. I think helping to setup the Pro-C for this would open a market on its own for the video editors on Premiere.
Probably it is possible already. But I did not see how. There are channel settings in premiere that even say sidechain and look promising but I gave up soon (probably too soon).
Looking forward for answers.
Keep up the good work.