I just bought a 1992 4 runner with 3.0 V6 and auto transmission. It has auto locking/disenganging hubs. Is there anything special I need to do to engage and disengage the 4 wheel drive such as backing up when going out of either 4H or 4L and into H2? I am going to use this car at hunting lease with a lot of sand.

 

You don't have to do anything special, unless you're shifting to L4. To move to L4, you need to reduce speed.

From the manual on my 93. Page 56 (d) Shifting Procedure:

Shifting between "H2" and "H4"
To shift from "H2" to "H4", move the front drive control lever with the lock release button depressed.
The indicator light may not come on even if you shift into "H4". If the vehicle is stopped, starting out the vehicle will turn it on. If the vehicle is moving, depress or release the accelerator pedal slightly.

CAUTION:
Never more the front drive control lever if the wheeels are slipping. Stop the slipping or spinning before shifting.

To shift from "H4" to "H2", simply move the front drive control lever with the lock release button depressed.

The vehicle may be moving at any speed. If you shift while cornering, you may feel a slight shock. This is not abnormal.

Shifting between "H4" and "L4"
To shift from "H4" to "L4", reduce your speed to less than 30 km/h (18 mph) and move the front drive control lever with the lock button depressed.

To shift from "L4" to "H4", simply move the front drive control lever.
The vehicle may be moving at any speed.