How do you code and H-drive middle wheels?
Lots of different ways, but get the value of the stick axis you want to use and then assign it to a variable. Put that variable in the motor command where the power number normally is.
If you are looking for tank drive + strafe:
motor[leftmotor] = vexRT[Ch3];
motor[rightmotor] = vexRT[Ch2];
motor[strafemotor] = vexRT[Ch1]; // channel 4 also available
If you’re looking for channel mixing (arcade control):
//assuming Channel 3 is forwards, Channel 2 is turning, and Channel 1 is strafing
motor[leftmotor] = vexRT[Ch3] + vexRT[Ch2];
motor[rightmotor] = vexRT[Ch2] - vexRT[Ch3];
motor[strafemotor] = vexRT[Ch1];