If you get a hold of someone's structures/works, and want them to generate, simply place them in the corresponding directories. The base directory 'structures' is located in the Minecraft data directory. It contains the following subdirectories:
Those directories are searched and loaded when you start the game. To reload, run the Command:reload during the game.
Structures, Inventory Generators and similar that will be loaded as inactive. Structures placed here, for example, will not appear in world generation.
Schematic files that can be imported using Command:exportschematic. These are not registered, but merely read during the command.