I am no expert on folders, I have made a few kits, and just recently finished my first complete build of a folder. But I do have a few tips.
The one pin on folders that will be a little difficult, is the one in the center along the bottom edge, that is the spring pivot pin, and it has some pressure on it from the spring, so you will need to hold against the spring, to relieve the pressure, so this pin can be replaced. A vice will work for this along with a piece of hard wood or brass stock the same thickness, or just slightly thinnner than the spring is. After removing the old scales, just get it all lined up in the vice, and squeeze it slightly, and remove the old pin, and replace with your new one. When peening this pin, be very careful not to over do it on fragile scales, being so close to the edge, it can crack easily. One way to eliminate that problem, is to countersink the holes in the liners, and peen that pin to the liners, and sand it flat and put the scales over it, this may not work on very thin liners though.
Hope this helps,
Dale