I've been meaning to mess around with auto-tiling in Construct 2, and this gave me an excuse to actually do it. Check it out:
Just like the article you linked to, I'm only setting a tile's frame based on the tiles above, below, and on either side, so some of the corners don't look quite right. The fix is to base the tile's frame on the 8 surrounding tiles, but it would require 256 individual frames (which I didn't feel like making).
Just for fun, I have the TileMap save/load from webstorage.
I hope this helps.