Token to show all the comments including comment body for a node
To solve your issue you can create custom token which contain needed info. Basically you create a module that implements hook_tokens and hook_token_info. For more details see the documentation: http://api.drupal.org/api/drupal/includes--token.inc/7. 

Additional, where you can find examples: 
https://www.drupal.org/node/1308488 and
How to programmatically create a custom token in a module