I'm terribly sorry to say that it is not... I actually found that part of documentation earlier by myself and it's quite frustrating. It only describes how to create a transformation map, but doesn't describe how to use them (I think I remember this being covered in the training material somewhere). Secondly, there is no description for how any of the masking functions that are available actually work. The descriptions are incredibly vague. And lastly and most importantly, there is still no description on how to add your own masking functions.
I'm beginning to suspect that this functionality doesn't actually exist, in which case the article I originally quoted is useless and confusing.