I followed the hillbilly method, and used a breaker bar with a socket, positioning the bar with the handle on the ground so the bar would not turn or move. Then, I turned the key, "starting" the engine for a second, and immediately turning it off (not a complete start). The bolt spun right out.
Is this the preferred method? Probably not. An air-powered impact wrench with the appropriate attachment is, more than likely, the best way.