You can do these with virtually any row set up. Ideally you'd do it with a chest-supported row so that your focus can be on what the scapula are doing without using energy to hold the torso in position.

Start by retracting the scapula and holding that isometric position for a few seconds, then finish the movement by pulling with the arms and getting spinal extension. Arch your back as you complete the movement.

Do these regularly and you should be able to go back to doing rows without the isometric hold before elbow flexion. You'll have trained that movement pattern so that you naturally start rowing by initiating with scapular retraction rather than elbow flexion.