Cut the door casing with a jamb saw so that the Shaw flooring -- including the underlayment -- can slide underneath without a visible gap.
Install the flooring up to the doorway as normal, stopping the plank before the plank that goes through the door.
Measure the first corner of the doorway and mark these measurements on the backside of the plank that will fit there. If one plank will be long enough to fit the entire doorway, mark both corners on the back of the board. Remember to account for the expansion gap.
Cut the marked corners out of the plank with a jig saw.
Measure the width of the planks to see if you will need to lay an additional piece within the doorway for the transition or if you will need to rip the plank to lay just under the door when it's closed and make the appropriate cuts. This isn't necessary if you are continuing the laminate through the doorway into the next room -- you'll just need to measure and mark the corners on the following row to account for the corners of the doorway.
Install the planks in the door way.
Install the correct transition molding -- transition molding comes in various styles for transitioning between the Shaw laminate and other types of flooring -- unless you are continuing the Shaw laminate.