add hook_for to ScaffoldGenerator

I want to add a new aspect to the ScaffoldGenerator and I wanted to do
something like this inside my railtie:

Rails::Generators::ScaffoldGenerator.hook_for :ixtlan

but is does not work and bails out with:
No value provided for required options '--orm'

on generators without an hook_for to orm the same thing works.

anybody has a little hint for me ?