It will seem impossible at first but it can be done. I didn't want to remove the snake bundle because 1-more work, 2-chance of vacuum leaks afterwards. It is not easy but is possible, i recommend several pairs of rubber gloves, plenty of time, and even more patience to start with.
-The best socket sets to use are 1/4" type and 3/8" type. Forget your 1/2" set its of little use here. Have At least one u-joint type socket connector, two is better.
Have socket extensions of varying lengths from the shorties to a 6" long one.
-Use masking tape to hold the socket extensions and the spark plug socket together, it will save you a lot of trouble of chasing down falling socket extionsions.
-The plug closest to the front (where the belts are) of the engine is naturally, easiest to access from the passenger side, the back one is best accessed from the drivers side. I accessed the middle one by actually laying down across the engine and going in from the drivers side opening. You can partly see what you are doing through the small gap in the plenum but you are going to do most of it by feel not by sight.
-the way i did it was this, i would guess which extensions would work then tape them together and to the spark plug socket. Leaving the socket wrench unattached, i would drop the spark plug socket onto the plug (after removing thec oil packs of course). After some trial and error and rearranging sockets and u-joint attacthments til i got the spark plug socket on, then i'd attach the wrench and loosen. With all the u joint attachments you might be using, you're turning the wrench at very odd angles, but you still ought to be able to get the plug out (hopefully it is not seized in place!)
-To put the new plug in: I always use high temp anti sieze on the threads (since i dont know if i will be doing this again on this car, but if i do i want to make it easy as possible next time.)
Put the spark plug into the socket and lightly secure it to the socket with one piece of masking tape maybe an inch or two long (so it will tear off easily). This is so the plug doesnt fall out as you go to put it into its hole.
Start the plug in by hand, by turning the socket extention. It should go in easily, if it doesn't, and you feel resistance, pull the plug out a bit and start over. You will feel when it catches the threads so keep turning it by hand until it stops. Then reattach the socket wrench and tighten firmly i.e. nice and tight, but not with all your might.
I don't know how you'd torque the plug doing this, since all the attachments are going to affect the torque reading and probably make it wrong. So i just get them good and tight but not white knuckle tight.