I have redeemed CO miles for J class travel on the EK JFK-DBX-JFK nonstops. Since you are trying to redeem a North America to Europe reward, however, EK might not be a valid carrier for that type of reward (series 6). See http://www.continental.com/web/en-US...1BB171927D98FF.

Continental Airlines OnePass rewards are valid for travel on Continental Airlines, Continental Express, Continental Micronesia, Continental Connection carriers, SkyTeam Alliance: Air France, Aeroflot Russian Airlines, Aeroméxico, Alitalia, CSA Czech Airlines, Delta Air Lines, Delta Connection (excluding Delta Connection flights operated by American Eagle), Delta Shuttle, KLM Royal Dutch Airlines, Korean Air, Northwest Airlines and Northwest Airlink. Other valid OnePass reward partners include: AeroRepública, Air Europa, Alaska Airlines, Horizon Air, American Eagle, Amtrak, Cape Air, Copa Airlines, Emirates, Hawaiian Airlines, Island Air, and Virgin Atlantic.

Not all rewards are valid on all airlines.