Converting theme widgets to plugins?

i need a help,
i have a theme, where in i have a twitter widget, i just want to separate it, and keep it in different file, as if it is a plugin,
here are is the complete code,
what i have to do?

this code was in file admin-functions.php

/*-----------------------------------------------------------------------------------*/
/* Twitter's Blogger.js output for Twitter widgets */
/*-----------------------------------------------------------------------------------*/

function woo_twitter_script($unique_id,$username,$limit) {
?>
<script type="text/javascript">
<!--//--><![CDATA[//><!--

    function twitterCallback2(twitters) {
      var statusHTML = [];
      for (var i=0; i<twitters.length; i++){
        var username = twitters[i].user.screen_name;
        var status = twitters[i].text.replace(/((https?|s?ftp|ssh)://[^"s<>]*[^.,;'">:s<>)]!])/g, function(url) {
          return '<a href="'+url+'">'+url+'</a>';
        }).replace(/B@([_a-z0-9]+)/ig, function(reply) {
          return  reply.charAt(0)+'<a href="http://twitter.com/'+reply.substring(1)+'">'+reply.substring(1)+'</a>';
        });
        statusHTML.push('<li><span>'+status+'</span> <a style="font-size:85%" href="http://twitter.com/'+username+'/statuses/'+twitters[i].id+'">'+relative_time(twitters[i].created_at)+'</a></li>');
      }
      document.getElementById('twitter_update_list_<?php echo $unique_id; ?>').innerHTML = statusHTML.join('');
    }

    function relative_time(time_value) {
      var values = time_value.split(" ");
      time_value = values[1] + " " + values[2] + ", " + values[5] + " " + values[3];
      var parsed_date = Date.parse(time_value);
      var relative_to = (arguments.length > 1) ? arguments[1] : new Date();
      var delta = parseInt((relative_to.getTime() - parsed_date) / 1000);
      delta = delta + (relative_to.getTimezoneOffset() * 60);

      if (delta < 60) {
        return 'less than a minute ago';
      } else if(delta < 120) {
        return 'about a minute ago';
      } else if(delta < (60*60)) {
        return (parseInt(delta / 60)).toString() + ' minutes ago';
      } else if(delta < (120*60)) {
        return 'about an hour ago';
      } else if(delta < (24*60*60)) {
        return 'about ' + (parseInt(delta / 3600)).toString() + ' hours ago';
      } else if(delta < (48*60*60)) {
        return '1 day ago';
      } else {
        return (parseInt(delta / 86400)).toString() + ' days ago';
      }
    }
//-->!]]>
</script>
<script type="text/javascript" src="http://twitter.com/statuses/user_timeline/<?php echo $username; ?>.json?callback=twitterCallback2&amp;count=<?php echo $limit; ?>"></script>

`

and this second code i found in theme-widget.php

`

/*---------------------------------------------------------------------------------*/
/* Twitter widget */
/*---------------------------------------------------------------------------------*/
class Woo_Twitter extends WP_Widget {

   function Woo_Twitter() {
       $widget_ops = array('description' => 'Add your Twitter feed to your sidebar with this widget.' );
       parent::WP_Widget(false, __('Woo - Twitter Stream', 'woothemes'),$widget_ops);      
   }

   function widget($args, $instance) {  
    extract( $args );
    $title = $instance['title'];
    $limit = $instance['limit']; if (!$limit) $limit = 5;
    $username = $instance['username'];
    $unique_id = $args['widget_id'];
    ?>
        <?php echo $before_widget; ?>
        <?php if ($title) echo $before_title . $title . $after_title; ?>
        <ul id="twitter_update_list_<?php echo $unique_id; ?>"><li></li></ul>   
        <?php echo woo_twitter_script($unique_id,$username,$limit); //Javascript output function ?>  
        <?php echo $after_widget; ?>


    <?php
   }

   function update($new_instance, $old_instance) {                
       return $new_instance;
   }

   function form($instance) {        

       $title = esc_attr($instance['title']);
       $limit = esc_attr($instance['limit']);
       $username = esc_attr($instance['username']);
       ?>
       <p>
           <label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:','woothemes'); ?></label>
           <input type="text" name="<?php echo $this->get_field_name('title'); ?>"  value="<?php echo $title; ?>" class="widefat" id="<?php echo $this->get_field_id('title'); ?>" />
       </p>
       <p>
           <label for="<?php echo $this->get_field_id('username'); ?>"><?php _e('Username:','woothemes'); ?></label>
           <input type="text" name="<?php echo $this->get_field_name('username'); ?>"  value="<?php echo $username; ?>" class="widefat" id="<?php echo $this->get_field_id('username'); ?>" />
       </p>
       <p>
           <label for="<?php echo $this->get_field_id('limit'); ?>"><?php _e('Limit:','woothemes'); ?></label>
           <input type="text" name="<?php echo $this->get_field_name('limit'); ?>"  value="<?php echo $limit; ?>" class="" size="3" id="<?php echo $this->get_field_id('limit'); ?>" />

       </p>
      <?php
   }

} 
register_widget('Woo_Twitter');

i just want this code to be a different file, just like a plugin, so that i can use this in my another theme also,
can anyone help me here???