lol, you need sparkedit, you open bg in se and go to tools-import tag into scenario, a box will come up, it will all be set, just press import, or whatever, and it'll be in there.
Then, you go to vehicles at the side, choose a vehicle, duplicate it, and then go to right and choos c_gun turret, put up to four, adn then save, vioala! you have them in, lol. Easy.