So I wondered if you could add an easy way to add a custom structure to the /locate command, I think it would be best to put it in the WorldGenerator class and then like this (using a structure from my mod, the generate method):

while (worldIn.isAirBlock(position) && position.getY() > 2) {
		position = position.down();
	}
	if (!IS_GRASS.apply(worldIn.getBlockState(position)) && !IS_HIGH_GRASS.apply(worldIn.getBlockState(position))) {
		return false;
	}
	if(IS_HIGH_GRASS.apply(worldIn.getBlockState(position))) {
		position = position.down();
	}
        Random random = worldIn.getChunkFromChunkCoords(position.getX(), position.getZ()).getRandomWithSeed(987234911L);
        Rotation[] arotation = Rotation.values();
        Rotation rotation = arotation[random.nextInt(arotation.length)];
        ChunkPos chunkpos = new ChunkPos(position);
        StructureBoundingBox structureboundingbox = new StructureBoundingBox(chunkpos.getXStart() - 16, 0, chunkpos.getZStart() - 16, chunkpos.getXEnd() + 16, 256, chunkpos.getZEnd() + 16);
        PlacementSettings placementsettings = (new PlacementSettings()).setRotation(rotation).setBoundingBox(structureboundingbox).setRandom(random);
        MinecraftServer minecraftserver = worldIn.getMinecraftServer();
	TemplateManager templatemanager = worldIn.getSaveHandler().getStructureTemplateManager();
        Template template = templatemanager.getTemplate(minecraftserver, HOUSE);
        template.addBlocksToWorld(worldIn, position, placementsettings, 20);
        *this.addStructureToLocate(position, "House");*
return true;

The params being: A BlockPos, obviously for where it generated, a String which is the name to use in the command

It would look something like this in the WorldGenerator class:

    protected void addStructureToLocate(BlockPos pos, String name)
    {
        CommandLocate.STRUCTURES.add(name);
        CommandLocate.addStructureLocation(pos, name);
    }

And in the CommandLocate class itself:

    public static String[] STRUCTURES = new String[] {"Stronghold", "Monument", "Village", "Mansion", "EndCity", "Fortress", "Temple", "Mineshaft"}
    public List<String> getTabCompletionOptions(MinecraftServer server, ICommandSender sender, String[] args, @Nullable BlockPos pos)
    {
        return args.length == 1 ? getListOfStringsMatchingLastWord(args, STRUCTURES): Collections.<String>emptyList();
    }
    public void addStructureLocation(BlockPos pos, String name)
    {
        don't know how to do this but you might get the idea
    }

I don't really know how lists sets and all work but jeh... gtg

Awesome, also hooks for MapGenStructure would be nice, and I mean like worldgen hooks, to add to vanilla generator.