2008 OFFICIAL GRAND SLAM RULE BOOK (page 26):
i. Lucky Losers
Lucky Losers are those players who have lost in the final round of the Qualifying competition or, if more Lucky Losers are required, those players who have lost in the previous qualifying rounds. Lucky Losers shall be randomly drawn.
The Lucky Loser list will be posted each day at least one (1) hour prior to the sign-in deadline which will be one-half (½) hour before the first point is played in the first match. Such list shall not be available for sign-in on the preceding day.