Here's how they did it at the 2010 World Boardgaming Championships and at EuroQuest:
BIDDING FOR SEAT POSITION, STARTING WITH THE QUARTER-FINALS: Starting with the quarter-final round games and continuing in the semi-finals and Final game, we will use mandatory bidding for all four seats. It will work as follows: Each player will randomly draw a random plantation tile (using the trading house values) to determine who bids first. For bidding in the semi-final round games, anyone advancing with a second place finish in the quarterfinals must pick last at his/her table (and hence will be assigned the lowest valued plantation). Similarly, anyone advancing to the quarterfinal round games with fewer wins will be assigned lower valued plantations than those with more wins, who shall be assigned higher valued plantations and therefore be among the first to bid.
Going around in plantation order value (coffee goes first), each player will place a matching plantation tile on a bid value ranging from 0 to 5.0 VP (in increments of 0.5 VP) on a chart to be furnished by the GM. Bids may be zero but in all instances must be higher than any previous bids for a particular seat. Any player who has been outbid will have his/her marker removed and will, when his or her turn comes, bid again--either a higher value for the same seat or a different amount for another seat. A player whose bid is not topped by another bid does not get another bid -- instead the bidding goes around to the next player without a bid marker in play. The process continues until all players' bid markers are on a different seat, with the resulting bid representing the VP handicap to be assigned for that particular game. These VP handicaps will be noted at the top of the particular seat position (1, 2, 3 or 4) on the scoresheet above the player's name and will be subtracted from that player's VP total at the end of the game.