Originally Posted by LupineChemist

You will be automatically routed to T4 from T4S. You exit the plane routed to a corridor above the departures level of T4S. Passport control is in the center of the terminal and then you will take escalators or a lift (you should take the lift) down to a train that will take you to T4. At T4 you will go up to the baggage claim area where (assuming you don't have to collect and re-check in) you can go directly through transit security located below the main departures hall. Take the lift all the way up to the lounge which is located above the main hall and shops in front of the main security checkpoint.