Originally Posted by
leroix
There is a somewhat hidden security line in TBIT as you exit customs (take a right instead of a left when you leave) specifically for connecting travelers in terminals 4/5/6/B -- it deposits you right at the connector between B and T4.
This is your best bet, and generally makes connecting to Ts 4, 5, and 6 relatively easy. However, not sure if it had been an aberration, but during my return several days ago, this section was closed. This was at or around 8 pm. If you find it closed, for whatever reason, you need to head out of B, then turn right and enter via T4 (AA), and can make your way to T6 via the tunnels. I'd say, assuming you walk at a normal pace, anticipate at least 30 minutes? If you have Pre, it may be quicker.