Knock Sensor Replacement and another Q

How time consuming and dificult is it to change the knock sensor buried under the intake manifold? From the looks of it its as hard as changing plugs on my camaro, damn near impossible. What tools to use?

2nd Question: Recently my SVX has experienced hesitation during start-up. I turn it over and nothing, i do smell gas though. Seems like the car is not gettting a spark but everything including the wires look fine???

Thanks