Even if you manage to have the 1K desk upgrade an S fare with an '02 SWU, there is a chance that you will be denied by an observant TA.

A few months ago I was checking in at LHR and the guy next to me in the biz class check-in line was having quite a row with the TA over just this. From what I caught of the conversation, he had been upgraded with a SWU on an S fare back to the states, but the TA wasn't going to allow it and was going to move him back to coach. I don't know how it turned out for him, but it didn't sound like he was winning the argument.