It can be done by a home mechanic who is a reasonably skilled machinist using decent equipment.The old valve seat is just an area of the cast iron head, so you need to machine this out using the valve guide as a center. Then press in the new seats with a hydraulic press.Depending on the siuation,you may want to put the seats in the freezer beforehand.Then accurately cut new seats for the valves.If you boot the job, and a valve seat falls out, it's goodbye engine,so be sure of what you're doing.
