Eh, se invece di guardarti attorno guardavi in Google evitavi di impazzire...
Devi inserire, nella cartella principale del tuo sito, un file .htaccess con i contenuti che ti posto qui sotto, opportunamente editati:
# .htaccess main domain to subfolder redirect
# Copy and paste the following code into the .htaccess file
# in the public_html folder of your hosting account
# make the changes to the file according to the instructions.
# Do not change this line.
RewriteEngine on
# Change yourdomain.com to be your main domain.
RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ [NC]
# Change 'subfolder' to be the folder you will use for your main domain.
RewriteCond %{REQUEST_URI} !^/subfolder/
# Don't change these lines.
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# Change 'subfolder' to be the folder you will use for your main domain.
RewriteRule ^(.*)$ /subfolder/$1 [L]
# Change yourdomain.com to be your main domain again.
# Change 'subfolder' to be the folder you will use for your main domain
# followed by / then the main file for your site, index.php, index.html, etc.
RewriteCond %{HTTP_HOST} ^(www.)?yourmaindomain.com$ [NC]
RewriteRule ^(/)?$ subfolder/index.php [L]
Poi, nel configuration.php, aggiungi una linea:
var $live_site = 'http://www.domain.com';