Domain map from root multisite

I install Domain mapping, I test it under subfolder : it works well
Question : is it possible to configure domain map from the root and not from the multisite ?
I explain
http://www.root-site.com/subfolder map to my http://www.new-site.com
Mapping's done from http://www.root-site.com/subfolder
Is it possible to do all site from the http://www.root-site.com ?
Thank you