This is what I want to do:
I have a domain: http://www.downhere.com
On that domain I will have a page that links to http://www.downhere.com/download.zip
download.zip does not exist, and will never exist.
If somebody tries to access download.zip (which dosnt exist) and they have a referer that matches my domain,
then I want them to be redirected to setup.zip
The end point is that I want anybody who tries to access download.zip without using a link on my site to get real 404 headers, but if they access the file from the link on my site I want them to be redirected to setup.zip