What i did, I went into the dashboard, changed the original url location for the blog under Options -> General to the new location name you want. (I did this on a test blog first though.) Say like you want: wordpress to now be: myblog then click Update Options button.
You’ll get a 404 page, close that window, then go into the FTP directory and change the folder wordpress to myblog, then delete the .htaccess file (Inside the newly named folder myblog). You then should be able to get back into the Dashboard (at the new url domain.com/myblog/wp-admin), go and update your permalinks and what not. Options -> Permalinks… then click the Update Options button. (This will then create a new .htaccess file automatically for you in the FTP directory.) You should be all set then…hope this helps. It worked for me. =)
P.S. After reading that information at the site you gave there, I’m going to go into the Database once and see if everything is correct there to. =) Yup, the way I did it worked and everything was changed via the phpMyAdmin, just don’t forget to change the path to file uploads then to, via the Dashboard. Options -> Miscellaneous Options. =)