For particular reason I don't like to look at that flag anymore. So I hacked my keyboard layout, changed it's name, flag and added missing Ukrainian-Cyrillic letters to it.
Copy 'Bandera.bundle' into /Library/KeyboardLayouts and go to language preferences.
Ukrainian-cyrillic keys:
- alt-и for і
- alt-й or alt-§ for ї
- alt-э є
Bonus keys:
- alt-е
- alt-ц