Cadillac Repair: remove/reinstall spark plugs, spark plugs, bulkhead

Question
Vehicle is a 1990 Sedan Deville and I need to change the spark plugs.  Engine sets crossways.  What all does one need to disassemble to get at the four plugs at the rear/dash bulkhead side of the engine?  It can't be as difficult as it looks.

Answer
YOU STATED: It can't be as difficult as it looks.

Oh YES it can. Everybody has their own method of getting them out. There is no right or wrong way, Just pick the easiest way you can find and don't forget to send a Thank You note to Cadillac Motor Division for the wonderful design.

There is ONE thing that does make it easier: Being double jointed.