If you think about the general way of bumping sheet metal, then you can use your imagination on many kinds of dents. In the case of a large dent, the usual process is to ruff out the dent by applying moderate to heavy force on the lowest part of the dent or crease, after that then use a hammer and dolly to massage the highs and lows back into shape. You might be able to get access in the trunk (if its behind the wheel) or remove the seat and side panel (if its in front of the wheel)
In this video you can see that he spreads the force out over a larger area to ruff out the crease by pulling, thereby getting minimun stretching or distortion from the blows.
http://www.youtube.com/watch?v=1nGalwR8 ... re=related But smaller repairs are done like you may have seen on stainless steel repairs. And that is working around and closing in on the major part of the dent. As you work the outer edges of the dent up, it slowly raises the center of the dent as you close in on it, and buy the time you get to the center there is quite often not much of it left.
Here is an example of the coming around the mountain approach, and there are many more videos here. I like the dentless repair videos because they show the principles of dent removal. Anyone using a lot of bondo, could just as easily use a lot less.
http://www.youtube.com/watch?v=ghb0nez4 ... re=related In some cases you might fashion some type of long punch with a blunt end to knock the dents down.
To control the point of impact it might take two people---one on each end of the long punch. Sometimes you can make a zig zag in your homade tool to get it out through the access hole, in order to strike it with a hammer.