Implement transliterator from Latin to Cyrillic and v.v. for Serbocroatian in similar fashion as it is done for Serbian. This is internally in Mediawiki called Language converter.
Link to relevant discussions on Serbocroatian wikipedia:
I was trying to resolve this myself but didn't have enough success. I'm not giving up on this so I'm including myself as being assigned to the task but any help would be much appreciated since I'm not sure I will be able to do it.