You should arrive at the TBIT.

Using the secure airside connector, arriving international passengers can clear Security after they clear USCBP, then proceed airside from TBIT to T4, and then take the airside tunnel to T6.

In T4, the access to the airside tunnel is from Gate 44 (look for "Terminal Transfer"). Take the escalator down to Gate 44, then turn left and take the escalator down towards baggage claim. At the bottom of the escalator make a U-turn to the right and enter through the double doors. There is an elevator located to the right of the escalators (inside a little hallway) that will take you directly to the tunnels. Walk the tunnel to T5 and then again to T6, and then take the escalator or elevator up to the concourse.

Map of airside tunnels.