Thanks, KC, but mine is actually just the opposite. Perhaps it is because mine is a manual transmission (3.0, d.o.m. 5/01) but the nut on the pulley for the hydraulic tensioner is definitely turned clockwise to relieve tension.

I got lucky on the broken bolt. After removing the radiator to have room for the drill, I was able to drill it and easily extract it. I actually used a screw extractor, for stripped phillips head screws, as my first attempt and it worked.