To do so, add the following line to the 'rewards' -> 'wargear' section of any mission.
The good news is that with the develper mode, you can unlock them all! However, the game comes with all of the war gears, it just doesn't let you unlock them all you can only unlock one set if you are lucky to buy it from one of the participating retail stores.
In order to entice folks into buying Dawn of War II at the retail stores and getting them to join the Microsoft Live Marketplace, various sets of different war gears are bundled as bonuses for different retail stores.
