How to use hook_theme in a custom module for print templates

I'm trying to override the print templates from my custom module, but I can't achieve.

I wrote my mymodule_theme function in mymodule.module. I can do it for node templates override, but I don't know which are the values for print module . Sorry but I do not know in depth the theme system.

function mymodule_theme($existing, $type, $theme, $path) {
  return array(
    'print__html__node__node_type' => array(
      'render element' => 'content',
      'base hook' => 'print',
      'template' => 'print--html--node--node_type',
      'path' => drupal_get_path('module', 'mymodule') . '/templates',
    ),
    'node__node_type' => array(
      'render element' => 'content',
      'base hook' => 'node',
      'template' => 'node--node_type',
      'path' => drupal_get_path('module', 'mymodule') . '/templates',
    ),
  );

What is the correct form ?