Autopainting Textures?

Would anyone here be able to give me a crash course on, or point me to a tutorial about, this mythical Autopainting feature for terrain texturing I have heard about? All the available material I have seen has been for the old editor.

I am having trouble learning the texturing process for an imported heightmap, aside from the regular 'point & click' brush approach - the map is just too big, I'd be at it for months.

Thanks for any insight you can give.