He was talking about z-buffer shadows IMHO. These can be switched on by adding
my.shadow = 1;
to the entity's action.
As far as I know, z-buffer shadow project onto any block that has been compiled in "shaded" mode, and behave according to the sunlight. Thus, I assume you'd also need to set a global sunlight to get the shadows working, but I'm not sure about this one. It has been a long time since I last used z-buffer shadows...