Although this is a pretty old thread, I'll throw my 2 cents in here.
I know of two ways to change the rear spark plugs,...
Hayes or Chilton manual says remove the Altenator to get to left side rear and the air intake on right side to get to the right sparkplug and from underneath to get the one in the middle.
My way, remove the Wiper tray and windshield wipers, remove the intake assembly, (make sure you have a new gasket for the intake manifold) remove the throttle body and disconnect all electrical and vacuum lines. Its a piece of cake, took about 4 hours to change my sparkplugs...
If ya do it my way, get the book, there are torque specs for the intake, plus the book is real handy before you start unplugging anything.