[Tom Bottiglieri]

You can use the ArcadeDrive method that takes raw values for the speed/turn inputs. This is the signature:

void RobotDrive::ArcadeDrive(float moveValue, float rotateValue, bool squaredInputs = true);

So instead of doing something like this

 myDrive.ArcadeDrive(myJoystick);

You could do something like

float orientation = 1;

if(goingBackwards) 
   orientation = -1;

myDrive.ArcadeDrive(myJoystick.GetY() * orientation, myJoystick.GetX());

You shouldn't have to reverse the motors with that.

EDIT: You shouldn't have to reverse the X axis actually. Kind of counter intuitive, but thats the way it works out. A left hand turn is a left hand turn looking forward and backward. You just want to change your direction. (moveValue)