At least for one participant you get to decide, though you can't write in just anyone (e.g. your blogger, yourself, or Mickey Mouse); rather, there are a list of 13 players from whom you can choose. The other nine slots will be determined by the organizers, six of whom have already been chosen.
For more details about who's in, who can be chosen and how to do it, when the tournament is and all the rest, have a look here.
HT: Hylen