Hmm, it appears the capx file has been taken down, but the link for the live version still works so you should be able to test it out. Basically, there's an object that defaults to the same position as you, and when you press to move in a certain direction, it moves there first to detect if the space is free or not. If the space is free, your sprite moves and if not, it doesn't. In the example the helper object is made visible as a green square but you would obviously want it to be invisible. I put the capx up on my dropbox (https://www.dropbox.com/s/dt3z6vohps1zn8n/topic68600_solution.capx).
Now that C2 has a tilemap object, I'm not sure if this would be necessary or not anymore. I haven't played around with it to test it out, but hopefully this helps in the meantime.