Adding another arg to comments_popup_link

what WordPress core functions do I have to modify to change

comments_popup_link('Ni komentarjev', '1 komentar','% komentarjev') 

to

comments_popup_link('Ni komentarjev', '1 komentar', **'2 komentarja',** '% komentarjev')

I’d like to add an argument for 2 comments. And what lines to add to this functions?

The reason why would I want to do that is simply the fact that in my home language we start plural by 3. I want it to be spelled correctly.

Filter 'comments_number'. You get the translated number and the real number as arguments. Return what fits best.

Sample code:

add_filter( 'comments_number', 'wpse_31328_comments_number_i18n', 10, 2 );

function wpse_31328_comments_number_i18n( $text, $number )
{
    if ( 2 === $number )
    {
        return _x( '2 comments', 'comments number', 'your_text_domain' );
        // or hard coded:
        // return '2 komentarja';
    }

    return $text
}