A really small screw and an even smaller drill bit? I had read on hack a day how someone was using acetone and abs plastic to "weld" but idk if the case of the n900 is abs. If it is you could just put a drop of it there to get a finger hold.

http://hackaday.com/2011/12/16/welding-and-casting-abs/

btw i think legos are abs