The CGI would key off what set of information to display based on either a parameter (retrieved using the CGI param method) or by using extra path information after the name of the CGI itself (retrieved with path_info). It'd then use that key to decide what to return.

That's pretty much it; not much more complicated than what you've already described.

Update: Ooh, yeah seconding the CGI::Application recommendation below. It provides a ready-made framework that does just this type of thing for you out of the box.