Multi-Model Forms

I want to update a form that contains logically grouped fields that
are contained across multiple models.

My models are:

user [act_as_authenticated]
profile [belongs to user]
newsletter [belongs to user]

Is there a way that I can setup my view so that in the controller I can

self.current_user = params[:user]

instead of having to specify each value individually for the separate
models? If that is not possible is there a way that I could code my
view so that I could write

self.current_user = params[:user]
self.current_user.profile = params[:profile]
self.current_user.newsletter = params[:newsletter]

Thanks for any help,