Force password change on email activation

Today I'm looking for a recipe to force drupal to change a password on activation email page on first login.

I tried to alter my user_reset_pass form,开发者_开发百科 and I know how to print password confirmation fields, but I don't have any idea how to override verification of that form to check if password is set and proper value.

Maybe You can give me some hints to do that?

Check this module out: Force Password Change