Per http://codex.wordpress.org/Changing_The_Site_URL , you can change the URL directly in the database, so you don't have to use FTP. Head on over to your DreamHost panel: panel.dreamhost.com and follow these steps:
- locate your Wordpress Database. To the right of it, you'll see Users with Access. Click on your username to retrieve your password.
*Head back to the MySQL Databases page
-under Web Administration, click "phpmyadmin"
From there, follow the instructions per the link
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