Take a look at the long thread by AiboPet, he had to gain access to it for his carputer, if you can't find what you are looking for there shoot him a private message and see if he can help you.
I've see pictures in the I.C.E. sub-forum of almost every speaker replacement but my quick search couldn't find the center speaker replacement, I'm pretty sure it was a guy who replaced all of the speakers.
If you remove the radio surround first it is easier to take off.Basically a ton of clips.The grill is deceptive.It's only a 3" in there and without major cutting not putting a 5.25 or bigger in there.I was hoping to get a coax 6.5 ,but no way.
I was told there was an 8" speaker in there! Seriously! That's jacked. I was reading in the brochure, and I was wondering where this amplifier is. Is it built into the radio? Or is it an order OEM thing?