I haven't used Socialite before today, so I did a quick install to see if I could reproduce the problem and ... wow ...
The system is definitely broken.
Facebook requires you to partially host your application on your own server. You set up some integration so you can use its API, but most of the work actually happens off-site. With other WordPress-Facebook integrations, you blog itself becomes the application ... Socialite seems to be hooking in to a system hosted by the plug-in developers as well. This causes a significant problem because your site then becomes dependent on an external system to function properly - an external system that appears to be malfunctioning at the moment. Also note that the last update to the system was made in December 2009 and the plug-in might not even be compatible with WP 3+.
The issue I see:
- The URL the plug-in sends you to is correct. Every application must ask your permission to do things with your account, and it gets at least that far.
- The callback URL seems to be broken. After authorizing an application, you're supposed to be sent to a specific callback URL (my guess is this will be the page that provides the "one time code" you enter into the plug-in configuration).
So for now, write Socialite off as "broken" and try another system. I recommend WPBook - it allows you to turn your blog into an application on Facebook, add it as a tab to your profile, add it as a tab to a fan page, and integrate comments between the two systems.