如何重写will_paginate方法

WillPaginate::ViewHelpers.pagination_options.merge!(     :previous_label => '« 上一页',     :next_label => '下一页 »'   )   module WillPaginate     module ViewHelpers       alias_method :orig_will_paginate,:will_paginate       def will_paginate(*args)         pagination = orig_will_paginate(*args).to_s  return "" if pagination.blank?        total_page = WillPaginate::ViewHelpers.total_pages_for_collection(*args);        total = hidden_field_tag "total",total_page        text = text_field_tag "text",nil,:size =>3,:maxlength=>5,        :onkeydown => "             if(event.keyCode ==13){                var  bl = !isNaN(Number($(this).val())) && ($(this).val()  != 0);                var p = bl ? ($(this).val() > $('#total').val() ? $('#total').val() : $(this).val()) : 1;                var h = document.location.href;                var url = h.indexOf('?')>0 ? h.substring(0,h.indexOf('?')) : h;                var href = url + '?page=' + p;                window.location.href = href;              }"        return "#{bb}#{pagination}跳转到#{aa}页"      end    end  end:onkeydown => "        if(event.keyCode ==13){            if($(this).val()==''){               alert('请输入需要跳转的页码!');            }else{               //判断输入的值是否为正整数               var bl = !isNaN(Number($(this).val())) && ($(this).val() > 0);               //输入的值小于1则取1，大于total则取total               var p= bl ? (Number($(this).val())>Number($('#total').val()) ?                    $('#total').val():$(this).val()): 1;                 var h= document.location.href;               var url = h.indexOf('?')>0 ? (h.indexOf('page=')>0 ? h.replace               (/page=.*&|page=.*/,'page='+p+'&'):h+'&page='+p) : (h+'?&page='+p);               window.location.href=url;}}"