To get to the back plugs your going to have to remove the intake or at least loosen the bolts, cylinder #1 doesn't need the intake removed as you can sneak the coil out but cylinders #3 and #5 coils will hit the intake and won't come out 
Removing the intake honestly isn't that hard at all, it's 8 bolts and you also have to remove the bolts from the power steering reservoir too. Other then that it's just the vacuum hoses. It would be best to pick up new intake gaskets from the dealer too along with the torque specs as there's a pattern to follow rebolting the intake together, the gaskets are cheap too.
You'll get to see how clean your intake valves are too doing this, good luck.
Removing the intake honestly isn't that hard at all, it's 8 bolts and you also have to remove the bolts from the power steering reservoir too. Other then that it's just the vacuum hoses. It would be best to pick up new intake gaskets from the dealer too along with the torque specs as there's a pattern to follow rebolting the intake together, the gaskets are cheap too.
You'll get to see how clean your intake valves are too doing this, good luck.