Middleman only works - as far as I know - in capturing the intermediate file(s) from the FS2002 and FS2004 plugins.
Why would you need to include middleman? If needed for your project, the person should instead be directed to where they can download it.... that would go around the possible implications of permissions, etc.
My 2-cents.
Well, I'm creating this package for use with FS9, which is what I have right now. And also, I can't find a place to download Middleman. The main objective of this download is to create a package that can simply be dropped into the Gmax folder without someone having to drag the net to find the correct files, and then name them correctly. I've done it two or three times, and it takes over an hour every time. This way, a Gmax user can simply drop this folder into their Gmax directory, and they're ready to go.