Make a spell server for OS X's system-wide spell checker to use arbitrary languages through libvoikko. See https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/SpellCheck/Tasks/CreatingSpellServer.html#//apple_ref/doc/uid/20000770-BAJFBAAH for more information
For further information and guidance on this task, you are encouraged to come to our IRC channel.