WordPress 2.0 and ErrorDocuments

I’ve recently moved my WordPress to my website’s root, and I am having a problem with my custom error (404, 403, etc) pages. It seems that the WP rewrite rules redirect any unknown page to the WP main index. I don’t want this behavor at all, but I am not sure how to go about making it work like it did before I moved the blog to the site root directory. Putting ErrorDocument lines in the .htaccess doesn’t do anything, it seems. How can I make my site do proper error redirects to my custom pages?