"working jog" and "working lope" are essentially the same as our working trot and canter. In the rules it states something about "to the horse's ability" I think. But anyways, as the WDAA representative doing the clinic in my area put it to the judges "It should be judged the exact same as a normal dressage test". Too slow/unrhythmical is penalized, head too low is penalized, behind the bit is penalized, shuffling gaits are penalized, etc..
WDAA uses USDF judges. It is judged like a dressage test. Honestly the outcome will be the exact same as a normal dressage class and eventually people with non-traditional dressage breeds will be complaining again how their horses are beat by the elitist snobs on horses bred for dressage, just now it's in different tack. As was suggested in a previous WD thread, it would be far more "WD" like to have a western gaming event, like pole bending or barrels, and then go do your dressage test and the combined score determines placing. Like in eventing.
Nothing wrong with a warmblood being ridden western, and capable of jogging and loping, but judging it as a dressage horse in a western event is just plain wrong and if I was the organizer of that show, I certainly wouldn't get that judge back.
We'll see how it evolves over time.