Be thankful that the IS has the instructions in the handbook, the GS manual says it has deadlocking but has no description on how it works.
However I have found out that one push of the key, locks the car a second push within 5 seconds activates the dealocking, however a second push if you wait longer than 5 seconds turns off the internal sensers and flashes the lights 5 times and leaves the deadlocking off.
So as Toyota often share components, has anybody tried the second press (waiting longer than 5 seconds to see if the IS works the same as the GS.
On the other point about the knobs on top of the dashboard, on the GS the one is the auto light senser (it also does the dash lights) the other is the A/C temperature senser, could the IS be the same?