has_many :through association

To make it a bit more clear:
in my form (for edit and new) I have the following:

<% for menu in Menu.find(:all) %>
  <tr>
    <td><%= check_box_tag "group[menu_ids][]", menu.id,
@group.menus.include?(menu) %></td>
     <td><%= menu.title %></td>
  </tr>
<% end %>

But this is not for what i would like ! (if it is even possible :stuck_out_tongue: )