Language modifications

Hello. Thank you for this plugin.
I would like to make it in my language.

I made a new aray with Greek characters and seems to work ok except one thing. In my language we have letters that are written like this: Α and Ά same for Ε, Έ – Ο Ό – Ι Ί – Υ Ύ and Ω Ώ.

I dont want to have then post (shown in the index). I am looking for a way to group them all so if a post title starts with Έ when someone press the E in the index to show him those articles starting with Έ τοο. Tried to add some alias to functions but no work. Any ideas how i can do that?