That page didn't say anything about glass; is it just an unwritten special property of every material with its surfaceprop set to glass (and presumably also whatever chicken wire is), or is there something more complex going on?
It's probably $transparent, $alpha and $alphatest in the material that enables light passing through, not the surfaceprop. The alpha layer of the texture then controls which parts are translucent. For models you have to add -textureshadows to VRAD if you want to have correct shadows for a fence, for example. As for brushes I don't think you have to specify anything special. Try setting up a little test scene if you really want to find out what's going on.