I did this when I sound deadened everything and threw in a complete audio overhaul into my car. I basically followed this guide:
http://www.flemworld.com/Mach460/Mach.html (scroll down to 'Rear Speaker Sound Board Removal')
Personally, I did version B as it was easier at the time since my interior was in pieces anyway. Whatever method you decide to do, make sure you unplug and speakers AND every connection that is made by that long ass duct taped set of wires. It's best to have something prop up the sound board while you make the final disconnects as one might guess, it will start to drop. Once the sound board was out, I just hide that huge chunk of wires behind the carpeting where it came from.
Good luck man and let me know if you have any questions. It's fairly straightforward.