How do you make a cat a barn cat?

I've tried twice. Wife ends up babying it and takes it in house. Then all they do is want back in house. So, I presume you put em in the barn and never ever let them in the house. Is it simple as that? Do you give them much attention, petting them and such or do you avoid them as much as possible? I need a barn cat. But mine is currently sitting on the back of my wife's recliner rocker looking out the window. LOL A major FAIL.

How do you make a cat a barn cat?