Domain Mapping in Subdirectory WPMU Installation

Hi Everyone,

I have a WPMU site hosted on a subdirectory (http://ogerente.com.br/rede). Nevertheless, my IP address 200.234.193.156 points to the root of the website, where there is no WPMU install...

Is there a way that I can use domain mapping in this situation? When I map a domain to the IP address above, it (obviously) just goes to the initial screen...

Thanks!