With the dash pad off, grind the old rivets off from the back. If you have replacement rivets, all you have to do is use a good pop rivet gun to reattach. Put a small piece of tape on the pop rivet gun head though, to prevent scratches to the plate. It'll take you longer to get your stuff together for this, than it will to grind off, then reattach.
So far as the removal of the pad, my car is a Barracuda and that process is described somewhere back in the archives, maybe 2 months ago. Don't know about your car specifically, but it shouldn't be that much different (I may be talking out my butt on that though.....).
