As of now, the only option is to use the SkyTeam international upgrades option but that is usually only valid with full Economy fares. Go to http://www.skyteam.com/about/miles/index.html (near the last half of the page).
According to this though, you would have to book on the AF code on AF-operated flights in either Y or S classes if you intend to upgrade on an AF-operated flight.

Since the OP is traveling next year, who knows what kind of upgrade scheme would be in place by then, especially given the AFKL-DLNW JV - perhaps the current upgrade scheme would be expanded and interchangeable on AFKL and DL?