Help me understand the ARB Air Lockers...I understand the basic purpose and function...but how do they relate to a CDL?

On a 2002 Disco, I have neither a CDL nor an easy route to activating one. If I were interested in putting in Air Lockers (and I'm not ready yet, but if I get to that point), can they be installed directly on the truck as is, and function effectively? Or do I first need to install a CDL and then install Air Lockers?

If it's the latter, the best route to a locking differential is probably getting the most I can out of my Disco and then perhaps upgrading to a 2004 at some point. Had I understood Disco's better to begin with, I probably would have shopped around for a 2004, but I'm still enjoying my first Land Rover....

Or is there another route with a 2002 Disco that doesn't have the infamous "nipple"?