I assume you mean have the people on the seating planks shoot with their weapons from the chopper. I am not on the BAS team, but I am 95% certain the answer unfortunately is no. Although having cargo positions in vehicles that can be fired from would be insanely cool, it is simply not supported by the game's engine, unless BIS finds the time to code it in for a patch, which is doubtful.
Some editor may yet come up with some clever solution to allowing multiple gunner positions on vehicles, or allowing soldiers in cargo to use their personal weapons, but I would not count on it.