If you perform secret command prompt options and run map2dif specially, it works backwards.
There aren't any.Read this:http://tork.beffy.de/tutorials/Hammer_WorldCraft/map2dif.php
They just open the default textures and edit them in paint or whatever. Torque interiors aren't like maps in other games where the textures are stored in the map file, just unzip map_bedroom.zip or whatever it's called and edit them.