Elke,
Doing the same thing as we speak. I've found that first use aircraft stripper. Buy a 2" wide metal scraper and a 2" wide plastic scraper. I use the metal scraper to get all the old bondo off and the plastic one for general use. It'll take many attempts since the stripper doesn't penetrate well through the bondo. I've found the best way to deal with it is to lay the stripper on the bondo and cover the area with some plastic film, this way the stripper doesn't dry up!(I can already hear the jokes coming so be prepared!) Make sure you let the stripper sit for at least 15 to 30 minutes so that it penetrates the bondo then scrape like a madman! Oh yeah, steel wool is good to get all the little stuff off but be careful because it loads up pretty quickly and you'll go through a lot of it if you don't try and get as much off with the scraper. One other thing, to keep the mess to a minimum I've found that you can use a small cardboard box to wipe off the paint sludge that develops on your scraper as your working. You just wipe the scraper on the edge of the box and it falls into the box. Good Luck and post some pics of your progress. I'm going to post some progress pics this weekend!