Rails - Jun 2006 - has_many / : through / check_box - update problems

Can anyone help me with this, which has been making me tear my hair out for 2
days now ?

I have the following classes using has_many :through relationships...
(I''ve changed the class names to make it easier to understand, so
don''t
beat me up about naming conventions ;) )

class Movie < ActiveRecord::Base
	has_many :localdetails
	has_many :territories, :through=>:rights
end

class Territory < ActiveRecord::Base
	has_many :localdetails
	has_many :movies, :through=>:rights
end

class LocalDetail < ActiveRecord::Base
	belongs_to :movie
	belongs_to :territory
end


The tables contain the usual *_id fields, and all display correctly, 
so no need to worry there.
Localdetails contains extra info, including a "will_be_shown_here"
field

I''ve got code that makes sure that for every Movie-Territory pair,
there
is a record in the localdetails table

While in a Movies controller, I want to loop through each Territory and
display a line which allows editing of the localdetails for that Movie 
for each Territory, something like...


for territory in @territories
  localdetail=LocalDetail.find(:all, :conditions[''territory_id=? AND
   movie_id=?'',territory.id,@movie.id])

 
check_box(''movie[localdetail_id][]'',''will_be_shown_here'')
end


But I can''t find any form of syntax for the checkbox that will allow 
this to work. 

I think I''ve tried everything, but of course, you may know better...

Any ideas ?