If you want php5 as default for a particular folder just add the following in an .htaccess file for the folder you want to use PHP5.  AddHandler application/x-httpd-php5 .php .php4 .php3 .phtml

If you would like to use php5 as default for your whole domain, please submit a ticket requesting this.  We will need to add: AddHandler application/x-httpd-php5 .php .php4 .php3 .phtml to the VirtualHost directive of that your account in the httpd.conf file.