I have a magpul trigger guard I want to put on and the KNS antiwalking firing pins.  As a newbie, can someone tell me step-by-step how to do these without marring my reciever.  Also, what to look out for - seems there's a roll pin on the factory trigger guard that looks like it just needs to be pushed out, but how do I get the othe "pin"/screw out.  Also, do the firing pins just push through?

Thnaks in advance.

yes the fire control pins just push through. use a punch of appropriate size and gently tap out the fire control pins, just becareful and you shouldn't scratch anything.  

Same with the trigger guard pin, however since it's in much tighter, when you remove the trigger guard roll pin use a wooden support with a hole to prevent scratching the finish or breaking the trigger guard ears on accident.  Line the pin with the hole so it clears the support when you punch it out.  The other "pin" is actually spring loaded, so just use a bullet tip or a small rod and push it in, then swing out the trigger guard.