While I’ve never done this myself, I’ve often dealt with or just observed those that do, and the short answer is that it boils down to a combination of social engineering and a good understanding of game mechanics in general, and Crimewatch in particular, which are quite complex.
An example of the use of the game mechanics for this would be suspect baiting in some ship to get a limited engagement, then bringing an alt in an Orca or a Bowhead to switch to another ship in space.
The social engineering part is the most interesting, though. A simple example would be having a friend or an alt engage you while you’re suspect to make your target believe he has a good chance to kill you together, but it can be much more complex than that. There are players that go as far as managing to trick their victims to suicide gank them in their expensive ships, which causes the victim not only to lose that ship, but then also yet another one sometime later because of the KR.