Hey man,
I will be having the same difficulty that you are in a couple days. I just got my Spec V the other day, so I haven't had time to investigate very hard on the topic of removing the rear speakers. But, I can give you this advice. Check
http://216.40.240.33/images/stereo-s...r-speakers.jpg for a pictoral guide. I got this from B15Sentra.net. It is a pretty informative site.
The problem though, is that it tells you that you need to fold down the rear seats... well, I happen to have purchased a spec V without the audio fanatic package. It appears that without the fanatic package, I do not have the option to fold down the rear seats. So, If you, or anyone else has any ideas? I would love some help on this one!
Good luck! If you have fold downs, the instructions should help a bunch.