There's a Summary tab on the Properties pop-up for packages, and it has a section where you can add comments. When you then mouseover the file in My Computer, these comments are visible (example below).
What I'm wondering is, are there any adverse effects to doing this? Might it cause the game to barf up the package file, for example? Or is it safe to do and, given that you may not have an RTFM kicking around, worth doing so you remember what a hack actually does?
What I noticed just now is that it does cause the ol' date modified to be altered, which is fine if you're keeping track of version numbers but hell if you're going by datestamps