I have aarddict installed on my N900 and am using it happily. It gives me evil messages when I try to update it using App Mgr, but it still works fine. I don't remember well how I got it working, but I think I mainly ignored warnings and went ahead anyway. I'm like that.

Edit: I uninstalled aardict on my N900 and reinstalled with the install file for the N900 you mentioned. It worked, though I got a message saying it couldn't be installed. I think this is the same way I installed it before. I have a couple of dictionaries installed, so it's definitely working.