You're using the latest WIP?
In that case, you just need to put the keyboard.dat that comes with Allegro in a place where your program can find it, for instance the program directory or teh directory pointed to by the ALLEGRO environment variable.
That is, if a croatia keyboard mapping is available... I'm not actually sure that there is. In that case, allegro/tools/keyconf.txt should have information on how to make one. In that case, be sure to submit it so we can include it in a future release