I've only ever done 4 line master cylinders one way.
Install it on the car, fill it, put the bench bleed hardware on the front two ports, leave plugs in the rear. Press the brake pedal slowly 3/4 stroke careful not to bottom out hard, repeat until you feel the pedal firm up as good as it can get. Take the bleed hardware off, install the front 2 brake lines, pull the plugs from the rear ports, install bleeder hardware and repeat above until the pedal feels good. Install your rear lines and you're done.
The Lumina has a split diagonal system, meaning each of the two pistons works one front and one rear wheel. The proportioning valves are built into the master cyl, that's why it has four lines instead of two.
Have plenty of water near you and douse any leakage with it once you're done, so the brake fluid doesn't eat anything it falls on.