Default configuration for new fieldsets in vertical tabs doesn't work

Would it be possible to have some hook alter or something similar to add general settings to form fieldsets?

This way, it would be possible to change settings to fieldsets as #group to add it into vertical tabs, change weight, or title, or even add #attached to add any js or css to theme the tabs configuration.

It would allow customize the vertical tabs configuration for any module from a custom module.

Doing this change in a hook_form_alter is painful as it needs to be done on any node_form or node_type_form, and search for any fieldset in the form.

Now it is possible to active vertical tabs in system forms or custom forms using $form['#pre_render'][] = 'vertical_tabs_form_pre_render'; but it is mandatory to
add the #group option in existing fieldsets to have it working with vertical tabs.
If you are developing a module you can add it for yourself but there is no way to do it in external modules without hacking it.

Just adding drupal_alter('vertical_tabs', $elements); before the return $elements; in vertical_tabs_get_form_elements(), you can have a function like:

function mymodule_vertical_tabs_alter(&$elements) {
  if (isset($elements['print'])) {
    $elements['print']['#group'] = 'additional settings';
    $elements['print']['#title'] = 'Print, e-mail and PDF';
    $elements['print']['#weight'] = 30;
  }
}

Is there any other way?

I think that be dependent on all module developers to make this change could take time.
Some temporal solution to make compatible any existing module with the vertical tabs would be nice.
(I have understood that in D7 the core integrated vertical tabs feature will remove this issue, but in D6 vertical tabs is optional)

#incrn8 patch is other nice way

While we can find some easy way to make vertical tabs work everywhere, I will start opening issues (with the vertical tabs tag) in modules that I find need this #group property.

The form alter solution has an inconvenient, I found modules that are at a different execution level that my custom module and they don't take the
alter modifications unless I increase my module execution level.

Probably some instructions about methods to customize vertical tabs could go in the INSTALL.txt, or for module developers how to make his module vertical tab compatible (adding the #group property and even an js sample to customize the tab content)

The different methods I found are:
- form module (but is heavy lift module for production servers)
- custom hook_form_alter
- import a 'vertical_tabs_forms' variable (from a previous form module configuration)
- adding #group property in modules fieldsets
- any other?

I am very happy with this module I would like to use it intensively everywhere.