Just did this exact job on my 300E. Charles has pretty much summed it all up nicely. The only things I could add would be that there are three metal clips on each side which help to hold the rim of the back panel in place - one at the bottom, one in the middle and one in the top. If you start removing the panel from the bottom (which you should), you will require a good bit on initial force to pry free the first clip. Once you do, you'll see how the whole thing fits together and should have no problem with the rest of it. The tip about having someone sit in the seat during re-installation is very helpful!
When I was removing mine I noticed a kind of indentation or button about 2/3 of the way up on the back of the panel, slightly to the left when you look at the back of the seat. It pushes in but doesn't seem to do anything. Did anyone else notice this? What does it do? It is present on both seats. Just curious...
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired
"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon