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.

comments_popup_link()iscomments_popup_link_attributeswhich is not quite useful in your case; where is that line of yours located again? – soulseekah Oct 18 '11 at 5:53