I would never cut the lip off the well. As Luke mentions the integrity would be compromised and you're asking for more rust problems.
The use of fender rolling machinery is real nice. The Porsche 911 guys do this procedure quite often. I've heard of using baseball bats or PVC pipe. The instrument uses the tire as a leverage point. Very basic but many have done it this way.
The use of a heat gun is important in making the paint pliable. Others have used an Exacto or utility knife to control the paint crack on older or brittle paint. I would really try the heat method.
Here is another place which rents a rolling machine for $50.
http://www.robsaudiworld.com/fender.htm