Most of my logons have comments with the uifile.txt that tell you basically what each line does, and what modifying does to it.
Im going to be uploading a Doom 3 logon thats got better commenting and clearer section definition (as in, where the shutdown button is, where the welcome text is, etc). ive got it to show the "Welcome" text, the "windows is shutting down/starting up" text and some other things that logonstudio doesnt do, as well as how to reposition almost everything.
its a bit of code hacking, but its really the only way to get things to be exactly where you want it.