In lieu of a proper tutorial, here are some admittedly terrible text directions on how this works.
Vis Regions use the same basic pattern that is used in reflecting objects, as seen here
. The "Visibility Control" modifier needs to be set to "Normal" and have a Soft Volume
defining the volume in which the object(s) should be (in)visible. Protip: Korman will help you out on this if you use the soft volume object as the visibility control. For each object you want to be controlled by the vis region, you need to add the "Visibility Set" modifier and point it to the "Visibility Control" of the vis region.
Side note, while Doobes was working on the GoMePubNew Age, he found a bug with soft volumes in Korman 0.09 that can cause Vis Regions to behave incorrectly. It's fixed in 0.10, which should be appearing in the next few days.