This trophy must be unlocked in a ranked match as it will not unlock in Skirmish Mode or an unranked bot match. You will also need a minimum of two players so that your statistics for the match are not tossed. However, you can unlock this with no players on the enemy team, so if you want to boost, get some people together, turn off faction balancing, and have everyone join the same team with the settings set so that the missions go by as quickly as possible. Body Count will end in a draw, and you'll win everything else easily, leaving the final score at 6-0. Once again, please note that you may also be suspended from the Playstation Network if you are caught boosting, so do so at your own risk.
Of course, you can always play regular games and hope your team does well enough to get you the trophy. Although at this point, finding a game on this map without boosting or organizing a time to play regular, non-boosting games with others will likely be extremely difficult.