how are you able to get to it ? I see you need to take half the centre console off.

 

If that's to me, the switch is just behind the back of the front driveshaft on top of the transfer case. It is an odd shaped nut on a post. You just use the open end of a 10mm wrench to turn it clockwise to engage (it clicks so you know it is engaged). You can't see it from under the truck but once you've found it it is easy to put a wrench on.

There is a thread on how to make an actuator for about twenty bucks out of socket extensions, and it comes right up through the console.

 

I'm sorry... I should add: you just swing under the passenger side of the truck with the wrench.

It would be very inconvenient if you already stuck. I have only engaged mine a couple of times, in order to drive with the front drives haft off.