效果：

修改：mobile/templates/library/page_footer.lbi
在最后添加：

{if $qq.0 && $pname != 'goods' && ($pname !='flow' || $step !='cart' )}
<div class="foot-kefu">
        <a href="http://wpa.qq.com/msgrd?v=3&uin={$qq.0}&site=qq&menu=yes" target="_blank">
          <p class=""><img width="22px" height="22px" src="templates/images/product/ico-kefu.png"></p>
          <p class="">客服</p>
        </a>
</div>
<style type="text/css">
  .foot-kefu{position: fixed;bottom: 55px;left:0;height: 40px;width: 40px ;z-index: 200;margin-left: 2px;background: #fff;text-align: center;overflow: hidden;padding: 3px;border:1px solid #ddd;}
</style>
{/if}