Theme webform using custom module I know I could easily theme a webform using the webform-form.tpl template.

However, I want to do this on the module level where the tpl is located inside the custom module folder or coded directly into the .module file?

I tried looking in to these hooks and nothing seems appropriate for my need:
http://drupalcontrib.org/api/drupal/contributions!webform!webform.api.php/group/webform_hooks/7
I guess you can put near the file your_module.module. Also your can put it into a nested folder. Keep attention: webform-form.tpl.php and that template engine is invoked at the last moment. It overloads all module templates.