I don't have the cure, but I have a pretty decent solution for MY problem...
My hives all have those nice, big, expensive outer covers with the sheet metal on top. This is where my ants like to nest - right between the wood and the metal. When I locate a problem, I swap the outer cover with an ant-free cover and carry it to the house. I grab my benzomatic torch and start heating the metal on the cover. It kills some of the ants and sends some of them packing... After a few minutes, I do the same thing again. After hitting it about 4 times with the torch, all the ants are dead or gone. It doesn't cure the problem, but certainly solves it for a few months.