Looks like a pretty simple procedurefrom what I can gather from the Illustrated Parts Breakdown. The Firing pin and spring, Parts 5&4 are held in place by the Firing Pin Retraining Spring, Part 3. This retaining "Spring" is really a Roll Pin, or a pin made from rolled spring steel, thats why they refer to it as a spring.
The retaining pin, part 3 holds the firing pin and spring in by passing through the notch in the side of the firing pin. That notch is over sized to allow the firing pin to move fore and aft to fire.
To remove the firing pin:
1. Cear the weapon.
2. Field strip to remove the slide.
3. Clamp the slide, upside down, in a vise using either wood, rubber or plastic blocks to prevent damaging the slide.
4. Using a steel drift punch, slightly smaller than the hole that the retaining pin is in, and longer than the thickness of the slide, and using a small brass or steel tap hammer, drive the retaining pin down, from the underside of the slide, out of the top of the slide, just far enough for the firing pin to be removed from the back of the slide. If done carefully, you can prevent damage to both the slide and retaining pin.
5. Once the firing pin is free from both the retaining pin and the drift punch you can remove the punch and the pin and spring should be able to be pulled from the back of the slide. Note: Depending on the amount of spring pressure of the firing pin spring, it may shoot the pin out of the slide when you pull the drift punch free. Be ready to catch/block the firing pin to prevent it and the spring from being lost. DAMHIKT Rolling Eyes
1. Reclamp the slide in the vice, right side up this time, so that the retaining pin is standing straight up.
2. Place the firing pin spring into the firing pin hole in the slide, just as it came out, then insert the new firing into the hole with the notch to the side that the retaining pin is on.
3. Press the firing pin into the hole, compressing the firing pin spring, WHILE driveing the retaining pin back down and into the hole. It helps to have 3 hands while doing this. Rolling Eyes It also helps to squeeze the retaining pin with a pair of pliers while driving it down, to compress the roll of steel that makes up the pin, if possible. Be sure to use a drift punch for the last few taps of the hammer to prevent damaging the top of the slide.
Hope this helps, and let me know if you have any problems with it.
I'll shoot you a pm with contact info if you have problems.