Hold a piece of scrap flooring material up against the door jamb. Place the undercut saw blade on top of the scrap piece of wood and use the wood as a gauge to hold the blade in place. Cut through the underside of the door jambs on both sides of the doors so you can slide the flooring material underneath.
Install your locking floor pieces as per the manufacturer instructions as close to the door as you can get with full pieces of material, sliding each piece into the slots against the other pieces. Measure and mark the cuts that will be going around the door using a tape measure and pencil. Keep in mind that you are hiding the actual cuts under the door jambs, so add an extra 1/4 inch to your measurements to provide extra material for the pieces to slide under the door jamb.
Cut the pieces of material on your miter saw. Place the material on the tray for the miter saw, hold it in place and pull the blade down into the material to cut it along your marks. Install the cut pieces just as you did the rest of the flooring material to finish the installation around the door jambs, slotting the tongue-and-groove sections together with the other pieces.