Not necessarily a hack, but a fast way to earn xp currently is to set up a private game. Make it on basilica and the game type seize ground. Set the points limit to 500 to make this process quicker. Essentially all you do is capture all 4 points giving you 800 xp and then the win which gives you the 250 xp. All of this done in about 3-4 minutes. Use the assault class.