I would just buy some little brackets that they make for your brand and use them to mount your right and left fronts at least a few feet away to each side of tv, as close to listening level as possible. If you have to put them up high, no big deal, just angle them down. sub can go wherever, it really doesn't matter. What matters with the whole setup is where you will be sitting vs. where the tv is. for the surrounds, just put them to the side, a little bit behind you, same brackets will give you the most flexibility. Don't get too hung up about the corner and room diagonal issue - just experiment a little and improvise. Speaker stands might be better for some of the speaks. If you had a glass door, then you could put a speaker stand in front of the fixed pane, or a bracket above it.
I don't know which system you need or which brackets, but here are some:
http://www.appliance-haven.com/Sony_WSWV10DS.html
Wow! Really good pdf link here:
http://www.sonystyle.com/intershopro...T-Guide1-1.pdf