You have a couple of options, the first is probably the best since your car is already painted. A small self tapping type screw can be put in place of the pin. Drill a very small hole in the exact location of the original pin and install the screw in the hole. Before you do anything find a screw that will secure tight to the emblem just like the original weld on pin. You may have to grind some of the screw head off to make it fit. Make sure the hole is drilled to the correct size to give the screw good bite. Once you are able to install the emblem I would remove it and back the screw back out and install some thread lock as you will not be running the screw all the way down tight to allow for the emblem to slide in between the head of the screw and the body.
The second method is using a stud gun that actually welds a pin just like the original in place. The only problem is paint will have to be removed in an area the size of a half dollar to ground the metal. This of course would require the proper tools and repainting of the area. I would try the first method and I think you will be fine.
