I don't usually remove the glove box. It does help to be double jointed though. Anyway find either the big hole or large rubber plug located about half way between the door and the firewall up at the very top under the dash. Also it helps to have two people. Take a piece of thin wire like .035" welding wire and poke it from the inside out and have the other person let you know when they see it. As you stand over the antenna hole the passage which actually goes through two layers of metal, will at a little bit of an angle but directly under that lip you see on the inside the hole. I use a long needle nose to grab the thin wire and then just electrical tape the new antenna cable to the wire and then pull it through. You can put a loop in the wire and hook it around the cable and then tape it if you are worried about it coming off. Be patient. Without the old antenna cable it can be a real bear!
OK, do the four screws fasten into the metal of the cowl itself. Because I don't see any screw holes around my antenna hole.I do have an old OEM antenna and It has the metal cover that
Covers the four holes on the base.