What is the way to remove the three spark plugs from the rear of a 2004 Ford Taurus SE?

Open the hood and remove the cover to the cabin air filter. Remove the three 5.5mm (7/32 inch) screws to the lower cowling and set it off to the side. This should provide lots of room for access. My advice is to only use the exact Motorcraft spark plugs that came in the car. In a pinch, Autolite plugs can be used. Buying a Gearwrench 80546 5/8-inch magnetic spark plug socket, which comes with a flexible 3-inch extension, will be a lifesaver. Remove the electrical connector from the COP, remove the 8mm hold-down bolt, and gently remove the COP. Clean the COP with silicone spray or WD-40. Gap the plug to spec. Lightly coat the porcelain portion of the plug and the top electrode with dielectric grease. Apply a very light coating of anti-seize compound to the spark plug threads, using a flux brush. Carefully install the plug and tighten to 96 lb.-in.

Anti-seize is no longer recommended since most spark plugs have an anti-seize nickel coating on the threads. However if you do apply anti-seize, reduce torque by 10%.

ASME convention calls for reducing torque specs 15 to 25%, when using a lubricant on threads. The above torque spec was adjusted accordingly. When I've asked several spark plug manufacturers (NGK and Autolite) about using or not using anti-seize compound on threads, they defer to the car manufacturer's recommendation--even on nickel threads. However, I agree with you that additional anti-seize should not be used on zinc chromate coated threads (it would be redundant); it should always be used, though, on black shell threads going into an aluminum block.