My solution was to set up a smart playlist that selects songs based on the content of the comments; in this case, the playlist looks for the text "iPod Mini" in the comment field. I created two AppleScripts I placed in iTunes' script menu, one to add selected words to the comments and a second to delete those same selected words from the comments. It works like a charm to easily manage my iPod mini's playlist.
I want to thank Doug's AppleScripts for iTunes for providing me with plenty of sample scripts from which I was able to piece together the following two scripts. To those whose scripts I borrowed the code from, I am sorry I did not keep track of the authors to give them proper credit. Note that because I pieced these scripts together, they probably are not the most efficient.
Add iPod Mini comment. Copy and paste the source into Script Edito, and save the script into your user's Library -> iTunes -> Scripts folder (create the folder if it's not there yet), and you'll have fast access to the script from the iTunes menu. You can select multiple songs at once and activate the script -- it will and add to all the selected songs in one pass.
Remove iPod Mini comment. Again, copy and paste into Script Editor, and save it as described above for easy access. This script will also work on multiple selections.

