[SOLVED]Preselect refinement label in Google Custom Search Engine

var searchOps = {'defaultToRefinement': '[YOUR_REFINEMENT_LABEL]'};
var searcher = new google.search.CustomSearchControl('[Custom Search ID]', searchOps);


Source: http://productforums.google.com/d/msg/customsearch/X2NBjMqyxPM/vsTXmxowJNQJ

Documentation: https://developers.google.com/custom-search/docs/js/cselement-reference?hl=en