How to change the time zone for a domain

You can change the time zone for a domain in a shared server.

If the server php is compiled with Apache (dso module)
You can use htaccess to set the time zone for a domain.

SetEnv TZ location

For suphp servers,
You need to create custom php.ini for your domain and add the following

date.timezone = "location"

You can get the time zones from http://www.php.net/manual/en/timezones.php