ability to define DB_CHARSET in v1.3.9?

[pizza392]

Create a new file for it:

/includes/extra_configures/my_db_charset.php

<?php define('DB_CHARSET', 'your_charset_here');

Do the same with: /admin/includes/extra_configures/my_db_charset.php

when should i add this file to extra_configures folder?
all tables have been installed in database, the collation is latin1_general_ci, is it too late to add this file? cause the database tables remain latin1_general_ci

perhaps i should change all ENGINE=MyISAM to ENGINE=MyISAM DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci before i install the cart ?

what do i change all latin1_general_ci to utf8_general_ci now ?