Remote data querying for Twitter Bootstrap 2.0 Typeahead without modifications

remote-typeahead.js

// Charles Lawrence - Feb 16, 2012. Free to use and modify. Please attribute back to @geuis if you find this useful
// Twitter Bootstrap Typeahead doesn't support remote data querying. This is an expected feature in the future. In the meantime, others have submitted patches to the core bootstrap component that allow it. 
// The following will allow remote autocompletes *without* modifying any officially released core code. 
// If others find ways to improve this, please share.

    var autocomplete = $('#searchinput').typeahead()
        .on('keyup', function(ev){

            ev.stopPropagation();
            ev.preventDefault();

            //filter out up/down, tab, enter, and escape keys
            if( $.inArray(ev.keyCode,[40,38,9,13,27]) === -1 ){

                var self = $(this);
                
                //set typeahead source to empty
                self.data('typeahead').source = [];

                //active used so we aren't triggering duplicate keyup events
                if( !self.data('active') && self.val().length > 0){

                    self.data('active', true);

                    //Do data request. Insert your own API logic here.
                    $.getJSON("http://search.twitter.com/search.json?callback=?",{
                        q: $(this).val()
                    }, function(data) {

                        //set this to true when your callback executes
                        self.data('active',true);

                        //Filter out your own parameters. Populate them into an array, since this is what typeahead's source requires
                        var arr = [],
                            i=data.results.length;
                        while(i--){
                            arr[i] = data.results[i].text
                        }

                        //set your results into the typehead's source 
                        self.data('typeahead').source = arr;

                        //trigger keyup on the typeahead to make it search
                        self.trigger('keyup');

                        //All done, set to false to prepare for the next remote query.
                        self.data('active', false);

                    });

                }
            }

<input type="text" id="searchinput" data-provide="typeahead">

How do I set the options using this method - I want to change the number of items it return to 20 instead of 8 - cant see how to change the options from the Javascript before onkeyup