This was years ago but I remember being quoted 45k SM TPAC. Whatever it is now, it's probably not worth it. I think the Skyteam upgrade awards only exist for PR reasons. Nobody knows how to do it, and the odds of something going wrong are high. Best case you end up in Business class for a lot of miles and $$$, worst case is you waste a lot of money on a Y ticket, a lot of time mucking about with agents. and end up in coach anyway
EDIT: This person stated it was 25k with a full Y fare. But it was over 10 years ago.
Skyteam Mileage upgrade program