The reason that it isn't covered much, is because there's not much to cover. Without oversimplifying it, but without making it any more difficult than it is, a watts link is two bars and a bellcrank.
As with any links in a suspension, the longer the bars, the better (within reason for packaging and weight). The further out you mount them, the more control they have.
Mount the bellcrank to the chassis on a vertically adjustable slider, not the differential. Only the ends of the links should connect with your axle. You can incorporate the watts link rod end mounts into your coilover mounts if you do it right.
Bellcrank adjuster
http://shop.ronsuttonracetechnology....=764820&c=7068