On both of my BMW's I just used the thin open ended wrench from a bicycle shop, about $6 from an on-line source. On the 535 it took about 4 sharp wacks with a regular hammer while wearing gloves "righty loosey" and it loosened up. The 325iC was tighter to get at and I had to jam a tire iron under the belt on a lower pulley to keep it from spinning, got that one with about 8-10 sharp wacks with the hammer. Others seem to have more trouble getting them off. Haven't heard about the Ford tool, let us know if you try that. Sure hate to have to forge one of Jeff's Orc blades just to get that nut off!
Good luck