I recently scratched my Nokia E61 quite badly. I decided to order replacement parts to replace the cover and the case. I don’t like service centers so I took the freedom to replace the cover on my own. The procedure will probably void your warranty, but then, how should they find out you changed the cover? As long you don’t break things it probably wont void your warranty from an their point of view.
In order to change the cover of my Nokia E61 I had to take it apart. I took a few moments to make pictures along the process. If you need instructions on how to remove the cover of your own E61, then follow the link to the E61 gallery.