does anybody know how you program the motors you plug in the battery expander?

i have to program my drive system to one joystick, the drive system has 4 motors, this is what i have

task main()
{
bMotorReflected[port1]=1;
bMotorReflected[port3]=1;
bVexAutonomousMode=false;

while(1==1)
{
motor[port1]= vexRT(Ch2)-(Ch1);
motor[port2]= vexRT(Ch2)-(Ch1);
motor[port3]= vexRT(Ch2)+(Ch1);
motor[port4]= vexRT(Ch2)+(Ch1);
}
}
Is there any way in which when we turn our robot, motor ports 1 and 2 can move in reverse instead of not moving at all, so it can turn faster?

The battery expander doesn't effect the programming at all.
For instance if you wire from motor port 1 to input A on the expander and then output A on the expander to a motor, the motor will be controlled by programing motor[port1]. Note that on the expander all the white wires are toward the center.