Custom tags(.cfm) do not need to be registered on the server. They can be used placing these .cfm files under any wwwroot directory.
Then, you may call the module by using CFMODULE tag to specify the location.
If you would like to call the module without specifying the path module then you may need to put the module in the same directory as your calling template.
You may refer to the article in how to use the custom tag: