Being that it has evolved into a hole, all you can do is cut out enough metal to completely remove the rust and weld in a new piece of metal. If I interpret your post correctly, its in the wheelwell? If thats the case, you don't really have to worry about getting the replacement metal piece the exact size/shape of the hole (since asthetics won't matter). Just slap a bigger piece of metal over the hole and weld it together. Make sure you use a good metal treatment like "metal prep 79" on it and primer/paint it when you're done.
That is the rear speaker area. There are wires and insulation inside the panel. Its very easy to get to just a few screws and clips.
I also have the hole problem but now I know where all the dust is coming from :roll:
ok thanks, i guess ill let the autobody guys look at it, the first guy who saw it said it should be fixable, and shouldnt affect the integrity of the car, which made my day, right after hearing that big 6 fire up on the first turn