Multiplayer > Xbox LIVE > Create a Match
Match type: Team deathmatch
Reward limit: 50
Time limit: 20 minutes
Whichever team is going first must cross the bridge. One person should stand on either side of the middle building. From a stationary position players will be able to snipe the other team members who spawn in three consistent spots on each side. The team getting killed does not need to move at all. Stop killing at 49 points and switch sides. The entire match will be finished in about 10 minutes. If playing with four people everybody should get about 25 kills.
25 kills per 10 minutes = 2.5 kills per minute
2000 kills needed / 2.5 kills per minute = 800 minutes = 13.33 hours
This is faster than VIP on Camp, which is about 40 kills per 20 minutes (16.67 hours). It's not really a big difference, but playing on Canyon is also a lot more laid back and leaves less chance for errors.