Note: This is a temporary hack to allow the simulation of Master Set 3 terrain in VirtualScape. Zzzzz is currently working on the next official release, which will make this hack obsolete!
VirtualScape has no facility for adding half-height tiles, so to add Shadow tiles you basically have to choose one of the other thin-tile types to replace. I've made a group of files that makes it easy for you to choose (and change) which thin tiles you want to convert at any given time.
Download the file, unzip it, and put all of its contents into your \Images\Normal subfolder.
Run (double-click) ShadowOneTimeSetup.batonce.
That's it. From now on, just run one of the following batch files to make the replacement of your choice:
Whenever you change which tiles you're converting to Shadow, you will have to close your 3D window (probably all of your 3D windows) and re-render. As long as you don't want all five half-height tile types in the same map, you can make pretty much whatever maps you want.