This has been discussed in previous posts.
No, you can't use Apache (or any other) web server with CFMX on Mac OS X -- only the Default web server installed by CFMX.
The reason for this is that interfacing CFMX (actually the underlying JRun) with another web server uses a platform-specific C++ connector module.
There is no connector-module for the Mac.
The connector is used to efficiently interface a 3rd-party web server, while protecting MacroMedia's intellectual property -- so this capability probably won't be available for the Mac until/if Macromedia releases a Mac CFMX product.
Sorry, but that's the way it is.
P.S. If you wanted to get creative, you could trap all Apache "page not founds", and write a PHP program that redirects any .cfm page requests to port 8500