Neil, if Dave W took two days to drill then you know its going to be a very difficult job. If you have any of the stud left as a slight raised portion then when you start to drill the drill will catch on the raised portion and the drill will wander resulting in a scratch, I doubt masking tape around the area will save you. You could very easily do more damage without hardly trying. You will need to flatten the surface, maybe using the dremel, but take your time and be careful, then use a centre punch to locate the centre of the stud before you drill, the centre punch will locate the drill and stop the drill from wandering, start with a very small drill and make the hole larger if you need to. The stud/screw extractors are a very good tool, they work well. My advice is, unless you are very confident in what you are doing, take the car to the dealer and go and have a coffee while they take the stud out, its going to be like going to the dentist for a filling, don’t even watch, its going to be painful. Good luck.
My suggestion to use masking tape to protect the paint was predicated on careful use of a Dremel cutting disc to cut a slot in what I had understood to be an exposed 2mm section of protruding stud and protecting the paint from any sparks that may be generated. Clearly, masking tape would provide no protection from a "wandering drill bit"... for that DaveW's suggestions above would clearly be better options.
