The first thing to know is, with certainty, what the cut is and then get the type of sights you want that match the cut. While the "Novak" cut is a common one, it is not the only one in common use so it's important to verify first.
Next, you can drift the existing sight assembly out r-to-l with a punch, and insert a new one l-to-r the same way. A much better system is to have a sight "pusher" which does it in a jig. If you have neither the punches, vice, and skill to do the job by hand, or the interest in buying a jig, then it's better left to a gunsmith. It's an easy job, but it's also easy to score up your sight or slide in a very ugly way if you don't do it properly.
