I've never really looked into javascript much, so please ignore me if I'm being a complete idiot. I seem to recall some of the Maps stuff on N95 being Lua...Anyway

I'm guessing MapsPlugin is a XPCOM library. Where on the file system would this be located and would it be compiled or interpreted. I have found several warnings in the index.html file for functions like pause, resume etc. within GuidanceMockup which may be implemented in the library above. It would also appear that the Guidance instance is called by several dispatch functions. pauseNavigation() for example calls this._guidance.pause().

I imagine if there is a call to this library somewhere to display the directions at a given time on route, an extra function could be added to the dispatcher, using some sound library, to play standard Ovi voice files.