structure you application like this
myapp/
assets/
/js
/css
/images
application/
system/
Now put the twitter js and css files in the js and css in assets of codeigniter
Then access them like this in your view file
<script type="text/javascript" src="<?php echo base_url('assets/js/jquery.js')?>"></script>
<link rel="stylesheet" href="<?php echo base_url('assets/css/style.css')?>" />
<img src="<?php echo base_url('assets/images/abc_image.png')?>" alt="" />