Yes, that oblong hole that you are referring to is the child safety lock for the inside handle. If you introduce a sharp pointy object (like a pen) and move the miniature latch visible in the hole in the oppossite direction you should be able to deactivate the inside door opener.
As in any other car, you will be only able to open the rear doors from the outside, regardless of the position of the lock mechanism.
Funny tha manual does not mention it, as it does in the manual on my cars. But again, my cars are Euro versions.
Oh, the window safety switch on the front ONLY blocks the operation of the rear power windows, it does not desable the door openers. One interesting detail: if you turn on the child safety window lock with the headlights on, the lights on the rear door window switches will go off (clearly stating that the rear windows have been disabled).
CL 500, 1998
S 500 L, 1998
E 320 T, 1995