Well, the only implemented code tables for now are WIN1251, CP866, KOI8R and KOI8U;
But if you are asking about the slug/tag generation, you actually don't need this. I am using Utf8ToAnsi procedure here, because in the Russian KOI8 table the Cyrillic letters have the same codes as the UTF8 Latin letters with similar sound.
After the conversion, the string remains valid UTF8 encoded, but all the Cyrillic letters are replaced with the respective Latin letters that can be read the proper way in Russian, Bulgarian, Serbian, etc.
In other words, the use of Utf8ToAnsi is simply a hack. In order to fix the special Latin characters you will need different code at all.