Yea, it's a pain in the ass but it can be done with an extension and a spark plug socket. Last time i changed mine (while the engine was in the car) was prob like 4-5 years ago and it took me like 30-40 min to get the back ones done. After leaning over the engine that long my back was killing me
NOT a fun job but worth it in the end. Also, make sure you put high temp never cease on the threads!