Not the method you are looking for but I already have a utility that's pretty well debugged that may fit your scenario. It's called TipOff
The idea is you download, then rename if you like, but whatever name the download has becomes the key when you add the comment. Right click on the downloaded file and select Properties. There's a Comment tab. You can type or paste a short comment. Then when you hover the mouse over a supported archive file, such as .rar, a Tooltip pops up showing the comment you entered.
The reason I wrote it is to comment downloads. You can comment any file but only supported types show in the Tooltip. But if you install TreePad there is built-in conversion to TreePad 3 file format of all the comments in a folder using a button on the same Comment Tab. TreePad Lite works with it. Both TreePad Lite and my app are free.
Since it works via 32 bit shell extensions it won't work in 64 bit OS unless you run a 32 bit explorer window while using it. You can download
Half Shell from the Hotkeys
page to make using it easier on Vista64.
When you comment files in a folder, a file is created in that folder named
CommentData.tof and since the data is local to the folder, you can copy entire folders, even to mapped networked drives and the TipOff will work as long as you have the shell extensions installed on the machine doing the reading.