Publish at
<%= check_box_tag 'live', true, params[:live], :onclick => 'toggle_published_at(this.checked)', :id => 'live' %> <%= f.datetime_select 'published_at', :disabled => params[:live] ? nil : 'disabled' %>

Publish till
<%= check_box_tag 'live', true, params[:live], :onclick => 'toggle_published_to(this.checked)', :id => 'live' %> <%= f.datetime_select 'published_to', :disabled => params[:live] ? nil : 'disabled' %>