Implementing autocomplete with Google site search

I'd like to implement autocomplet开发者_JAVA百科ions on a Google site search engine. This site uses the (paid) XML API however for customizing the results. Google's documentation only talks about autocompletion for the JS API with custom search.

Is it possible to fetch some XML or JSON feed with autocompletion data? Or is there some other way to achieve autocompletion without giving up on the XML search API?

I wrote my own autocomplete, see demo here: http://olegh.cc.st/autocomplete.html If you have your own dictionary, and own WEB-server on unix-like platform, you can run my autocomp. I can share sources for free.