The passes have to be purchased at the park. Here's the section of the news release that is specifically about WDW:
At the Walt Disney World Resort:
Each active member of the U.S. military may obtain a complimentary seven-day ticket during the offer period. This ticket, specifically created for "Disney's Armed Forces Salute," will be valid for admission into the four Walt Disney World theme parks, a Disney water park, Pleasure Island and more for seven days from the date issued.
Within seven days after receiving the complimentary ticket, each active member of the U.S. military may also purchase various special offer tickets at a 50 percent discount for up to five family members and friends. These tickets will be available for the Walt Disney World theme parks, Disney water parks, Pleasure Island, DisneyQuest or Disney's Wide World of Sports complex and must be used within seven days following the date of purchase. Each active member may only purchase up to five special offer tickets for admission to the Walt Disney World theme parks.
If active members of the U.S. military are unable to come to the Walt Disney World Resort during "Disney's Armed Forces Salute," their spouses will be eligible to purchase the special offer tickets one time during the offer period for up to five family members and friends (including the spouse) at a 50 percent discount. The special offer tickets must be used within seven days after they are purchased. Each spouse may only purchase up to five special offer tickets for admission to the Walt Disney World theme parks.
The complimentary and special offer tickets can be obtained only at Walt Disney World theme park ticket windows from January 1, 2002 through April 30, 2002. Active military personnel (or their spouses, if they are not present) must present proper military identification. Activated members of the National Guard or Reservists (or their spouses, if they are not present) will also need to show active duty orders. In addition, active military personnel will need to show their complimentary tickets to purchase special offer tickets.
U.S. active military personnel are also eligible for discounts at select Disney resorts, starting with a $49 per night rate (plus tax) at Disney's All-Star Resorts, available most nights from January 1, 2002 through April 30, 2002. The number of rooms available at this rate is limited and minimum length of stay requirements will apply to Friday and Saturday arrivals. Additional charges apply if there are more than two adults per room.