Yes, it's possible, but using symlinks is not the way to do it. You need to have access to the httpd configuration file for your site (possibly in http.conf itself, or (more likely) included into it) and the server's DNS configuration files as well. Depending on where you're hosted, they might have a Web-based interface for you to do this (e.g., CPanel). If you're hosting yourself, look up "named virtual hosts" (ServerAlias, specifically) in the Apache documentation and the documentation for whatever DNS you're using (often BIND).