I got an order to create ecommerce website with 3 languages - english, japanese, korean.
Since there are already japanese and korean language addons for oscommerce I decided to use oscommerce for this project. I have installed those language packages succesfully, however, when try to add category names in japanese and korean, the characters were demaged, and reflected worng. I spent few hours to sort out the problemm, and at the end found the solution. So how you can do:

1. Open admin/includes/languages/english.php

replace: define(’CHARSET’, ‘iso-8859-1′);

to: define(’CHARSET’, ‘charset=utf-8′);
in around line 45

2. Execute the following sql command in your mysql database
ALTER DATABASE `os17` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci

3. Change varchar to 255, in product name, and category name fields. Because when you use utf-8 you have 4 times more characters than usual.

Hope this will help someone too.