I have used this technique in off-roading now for over 10 years. The main purpose of this technique is to smooth the ride as you pass through uneven terrain, generally rock gardens but can be used in other situations too. The benefits of a smooth ride are for more than just comfort. Damage will be les severe or even non-existant in cases where clearance of vital components is compromised. Think of slamming your rig down on some large rocks versus gently setting it on them.
1. With your transfer in low gear and your AT in low, apply pressure to the brake with your left foot then gently apply pressure on the gas pedal to bring the RPM up to 1500 (this is the number I like, you will find your favorite in time)
2. Begin to release pressure off of the left foot ever so gently to allow the vehicle to creep forward.
3. As you begin to move through your uneven terrain, you will find that the vehicle will move trough the obstacle much more smoothly especially when dropping off on the back side of large rocks. Without the brake being applied, the vehicle will want to slam down but because the brake is applied, there is too much resistance for it to slam down and it just comes down soft and gentle (comparatively speaking)
A secondary benefit of this technique is what has also been mentioned here in previous posts which is to pre-load the drive train thus minimizing the numerous gears and joints slamming together every time the resistance increases and decreases as you're moving through the uneven terrain.
If you want to try this yourself in an AT, there is absolutely nothing to it and you will notice a difference within the first few seconds of doing it.
Go find an empty parking lot with concrete parking stops, drive over the parking stop in your normal "too lazy to back up" fashion, feel the bump as the vehicle drops of the back side of the concrete stop. Now do it again only this time, use the left foot braking technique. Smooth as ...... well you'll see

let's hear from ya if you try this.
