The Unofficial Oninit blog has an article with an English introduction on how to make IDSAdmin work with non-English locales: IDSAdmin with non-English DB ?
It's good to see people customizing IDSAdmin. The PHP code is there for anyone to modify for their own purposes. The problem the blog mentions "The current open beta version of IDSAdmin does not use Locale variables when it establishes connection to the database server" has now been logged and will be fixed by GA.
New Informix PDO Driver Version
An Informix PDO Driver for windows compiled against the latest versions of the driver and also PHP (version 5.2 and 6) has been released and is downloadable at the PECL4WIN site here: http://pecl4win.php.net/ext.php/php_pdo_informix.dll.
This means you should now be able to use the latest versions of XAMPP. I have not tested this yet but my colleague tried copying the latest XAMPP over his existing installation, with the new PDO driver, and reports that it is working.
IDSAdmin with non-English locales