Vex C++ Line Follower

So I’m trying to use a line follower to detect and ball and there’s no line follower in the robot config as a three wire device if using Vex C++. How do I declare to my robot that there’s a line follower and the port that said line follower is in?

vex::line line1( Brain.ThreeWirePort.A );

int main() {
  while(1) {
    Brain.Screen.printAt( 10, 50, "Line sensor %d", line1.value( analogUnits::pct ) );
    // Allow other tasks to run

Look at Analog_in.value to get the values for the three sensors. Just calibrate so you know a good threshold.