The 1st time I changed plugs I followed the service manual taking them out (removing outer & inner air boxes off) and it sucked! I now do them as described below and takes 15 mins.
1) Take off seat, outer airbox cover, and left side air scoop.
2) Pull boot off front cyclinder plug and use 5/8" spark plug socket & 5/8" combo wrench to switch out plugs.
3) Pull boot off rear cylinder with long needlenose pliers. Use 5/8" spark plug socket - swivel connector - 6" in. extension - and Ratchet.
4) Stick all this through the space circled in the picture. (I was too lazy to take the outer airbox off for the pic.) It basically gives you "direct" access to the rear spark plug. Use your left hand to go in behind the frame where the air scoop was, and guide the socket onto the plug and remove.
5) Put the new spark plug in using the same method or a length of 3/8" fuel line, using the left hand through the air scoop space to guide. Be sure not to cross-thread.