Actually only 5.0 is translated to indonesian ( you can see on demo ) but this version is still not yet released.
If you need in 4.X simply get Lang_id_ID.java file put in source code 4.0. making simply changes and compile. ( You can get information in wiki.openkm.com how to configuring development IDE ( development guide ), and then only must put the file from 5.0
http://openkm.svn.sourceforge.net/viewv ... ient/lang/
Add the propertly language in login.jsp and into mainmenu.java ( really it's not complicated ... but you need minimal java knowledge )