On the three vlv diverter, I've removed the diverter stem, but I'm not sure how the seat comes out. If it screws out, do you have to have a special tool for that or can I improvise?

As you can see by the seat image I've put up they unscrew counter clockwise and have a square opening. They make a removal tool,( see image)but I always take a screwdriver and jam it in to turn the seat out. Good luck, Tom