With the "original" WW2 era 1219Cs/USN-MK2s, the pins can be gently punched out using a punch the same size as the pin since the pins go all the way through the pommel and tang.
With the newer versions by Kabar (model 1217 and variants) and the shorties, the pins are "blind pins", meaning they only go part of the way through (a smidgeon over 1/2 way). I get them out by "spinning" them out using a drill bit. Since the 1217HC comes with a replacement pin, I haven't really worried about messing them up too much when I take them out. My removal method is to use a pointy center punch to start a divot in the pin and then use a drill & bit to "spin" the pin loose and out.
The shorties pommel pins are shorter but the same diameter than the full-size pins. For the only one I've replaced, I spun it out as I "normally" do and then went to a metal shop and bought a small piece of steel rod the same diameter as the pin I removed - 1/8". I ground off one end into a little point like the kit ones are made and then cut it a little long. Then I ground it off after it was set in.
If I am trying to replicate the handle grooves, I carefully use a small rat-tail file to SLOWLY rasp away the leather. On the shorty, my friend was happy with a smooth leather handle, so all I did was sand it down, first with using a 2x72 belt grinder for the quick and dirty shaping, followed by hand sanding to the final contours.