I'm kind of thinking about doing the same thing to my 240. The only way I could imagine using a baseball bat to roll fenders would be to use the grip of the bat as a lever on the wheel hub, and roll the bat around the inside of the wheel well. Not only would this be inaccurate, it seems it would also loose the natural shape of the well. I think you may be able to find a good place near you who can roll fenders for you, or you can just buy your own fender roller. Be weary of shops that try to whack you like $500 for two wells, being that you can pick up a roller and do it yourself at half the cost (and just sell the roller when you're done).
This seems to be a good price for a fender roller (plus, I’ll buy it off of you when you're done

).
http://www.eastwoodco.com/shop...31158
Also - remember, if you can't do it right, then don't do it. Be patient with whatever technique you choose, and you will be rewarded.