The test.prop item is used to spawn dungeons that have previously been exported. Simply right-click while pointing at the ground and holding the test.prop item and your dungeon will appear. Your exported dungeons are saved in .minecraft\config\Chocolate\Building\test You can put any .schematic files in this folder and they will spawn when you use the test.prop item. You will find a file in the folder named template.schematic. That is just a place holder. You will want to delete it before attempting to spawn your custom dungeon.
Dungeons spawned with the test.prop item will appear a Y: 64 in height. So the dungeon may appear to be floating or down in the bottom of a crater. To make your dungeon appear at a nice location on the surface follow the instructions in the Dungeon Exporting Guide.