Domain Mapping plugin question about URLs

With the Domain Mapping Plugin, can I map a sub-site on WordPress Multi-site install 3.0.1 to a URL like http://www.existingwebsite.com/here-is-where-the-multisite-exists

so that if, let’s say, the Super Cool Shoes company had a front page that was on another domain (http://supercoolshoes.com) but wanted a wordpress sub-site that was hosted elsewhere to link to http://supercoolshoes.com/externally-hosted-wordpress, would that work or does it always have to be the base URL http://www.multi-site-here.com?