A lightning is some sort of massive discharge of energy, which was accumulated from warm and cold weather mixing. So all you need is some kind of object, which seeks to recharge itself. Say some sort of huge capacitor (with an antenna of course), and you could probably create a larger chance for lightning to strike nearby this location. Thus staying near it, creating a possibility to severe the lightning.
This does not change my own personal belief, when Kishi write things like this, being it in his databook or the manga. After reading much of Naruto, I do believe I have a good interpretation of Kishi's way of writing. Thus in my understanding, Kakashi never directly severed a lightning. He simply would have no purpose for doing so, however, he somewhat proved that it would be within his capability, and probably about his max capability.
But of course you can understand it more literally than me, it does not matter to me, neither interpretations are wrong or right.