Rocking the engine forward with the 2x4 piece of wood is the trick. Leave the 2x4 in until done cause the engine won't sty forward otherwise. You can create just enough room between the engine and firewall to reach your hand/arm back there. Be prepared to piss & moan as your arm is scratched up though!
I also found removing the MAP sensor out of the way helps . Its located on the back side of the Intake Manifold (2 bolts). Also, using a couple long extensions and a universal joint on your socket allows you to reach the Plugs, but still operate th ratchet in the open above the engine.
Have Fun and don't buy cheap wires or you'll be doing it again sooner then you want to!