Actually it doesn't. You can't install directly onto Vista unless you have the latest release (5.04). Even Reflex accept this and state in their support that you have to install on an XP machine first and then copy the file structure across. This suggests that it doesn't put important stuff in the registry or System32 - rather it is wholly contained within the Reflex folder.
From his posts (and his PMs) it does sound that he is at least trying to do the right thing. He has stated that he has copied the contents to c:\program files\reflex to c:\reflex. This should be enough according to what the reflex site and you say. The fact that it's not working either means that he has missed something or it doesn't work on all Vista installations. Unfortunately he's not too clear on what he has actually done (step by step) nor what the reported problems are so it's quite difficult to help remotely.
If you just copy the files across I was wondering how the USB device drivers get installed. My Reflex directory has a executable called ReflexHIDInst which appears to set up the interface. Does this get run automatically when you run reflex.exe or must you do it manually. I don't think this is the problem though (not yet anyway) - Reflex will start up and run without the interface - just can't fly.
Perhaps he's hitting file permission problems especially if he is not running as administrator.