I have this form_for:
<%= form_for [post, Comment.new,], :remote => true do |f| %> <%= f.text_area :content, :cols =>10, :rows => 1%> <%
You should be able to set the form's id to whatever you want. Something like:
<%= form_for @object, :html=> {:id => 'custom_form_id'} do |f| %>