Edit Sitemap URL

Hi

I am trying to edit my sitemap url from http://www.mydomain.com/sitemap.xml to http://www.mydomain.com/mysitemap.xml.

I understand that version 3, this can be done through the settings function under the “Filename of the sitemap file”

How do I amend the sitemap url in version 4? I cannot seem to find the option available in version 4

Thanks and Regards
Bryan