Korean Air Skypass - Upgrading on Long flight

My fiance and I are flying Korean Air from Chicago to Seoul to Phuket for our honeymoon and would like to try to buy an upgrade for at least the long leg of the flight from Chicago to Seoul. We dont have enough points or status to come close to being able to get a comped upgrade. Is this possible to do before hand or do I have to wait for a day before to see if its available at the airport when we check in. We leave two weeks from yesterday. Ideally we would upgrade for the entire outbound leg of the flights from Chicago-seoul-phuket without having to upgrade on the way back. Any tips would be appreciated.

Thanks

From what I've gathered (aka when I called and straight up asked them( the only "upgrade" is a purchase from your coach rate to the prestige class rate......aka thousands of dollars. In other words, you should've just bought the cheapo biz class.

I have no problem doing that but had already booked it, now my question is whether i a) can do it a week before the flight and b) just do it for one leg of the flight.

My travel agent has been unhelpful in these answers.

I have no problem doing that but had already booked it, now my question is whether i a) can do it a week before the flight and b) just do it for one leg of the flight.

My travel agent has been unhelpful in these answers.

You could ask at the airport if you can purchase an upgrade. Korean Air doesnt have the the cheap upgrade program that outfits like Delta has.
There was a similar thread on this at http://www.flyertalk.com/forum/archive/t-533365.html