There are standard socket tools for removing f'ed up screws like that - available at Home Depot/Lowes etc. Bolt extractors etc...
http://www.irwin.com/irwin/consumer/...IrwinCat100497

I don't know how much room there is around the bolt head, but you could grind 2 flats on opposite sides of the head and use a regular wrench.
Use your imagination, but stay away from the alcohol this time.