Hi Gabriel, I had the same problem
What I did was, copy the whole error_messages_for method from ActiveRecordHelper http://api.rubyonrails.org/classes/ActionView/Helpers/ActiveRecordHelper.html#M000568
and put it in my /app/helpers/application_helper.rb
then I just hacked the part that builds the header_message
actually my quibble was the object name, not the column names - but you should be able to do what you like to it.
Maybe there is a better way though? seems this whole block of HTML should be in a view in any case.