Modify iTunes rating/advisory warning in mp3s on Mac?

I have searched and searched online for a solution and have found nothing that works.  I want to add & modify the CLEAN and EXPLICIT content advisory warning labels displayed in iTunes on mp3s using my Mac.

Yes, I know I could just type in explicit or clean in the comments field using get info, but that does not work with the built in parental controls.  Also, I get a little OCD with my music and would much prefer to use the correct label since there is one.

For anyone who says mp3 files cannot store this type of information, that is incorrect.  See the screenshot below for proof of the contrary.   I purchased the song below in the iTunes store but later converted it to mp3 so I could use the song on a device/program (can't remember which) that could not play the original file type.  The content advisory label was transferred to the mp3.

Here are some proposed solutions I found online that do NOT work:
- Atomic Parsley - Does not work with mp3s.  Yes, I could potentially convert my entire library to AAC and then use this but I do not want AAC files, I want mp3 files.  Mp3s are more compatible with other programs and devices.  I suppose I could also convert my entire library to AAC, adjust the content advisory warning labels, then convert the entire library back to mp3.  I do not want to do this, however, because of the potential to reduce the audio quality of almost every song I own. 
- Lostify - This program is for mp4 files.
- Atomic Parsley based programs - Again, they do not work with mp3s.

I may be asking for a miracle here but if anyone knows how to do this, an Instructable would be much appreciated.

On a somewhat irrelevant note, here is my take on the parental advisory warnings:  In an ideal iTunes world, these could be easily modified and protected by password so parents could make inappropriate songs not purchased on iTunes inaccessible to their children using the parental controls.  It seems ridiculous to me that this is not possible, as Apple knows that the majority of people do not have a library of songs 100% from the iTunes store.  Also some songs are mislabeled (oftentimes if one song on an album has an f-bomb, the entire album is marked explicit). 

Picture of Modify iTunes rating/advisory warning in mp3s on Mac?
DavidN713 years ago

You can add an image to an mp3 file in Windows Media Player. If your mp3's have cover art, a watermark on the cover art or just the Explicit Content jpeg would work.

http://www.macupdate.com/app/mac/30610/tagr Tagr works on OSX for mp3's.

Unfortunately, I don't think mp3 files have the capacity to have that kind of data (the clean/explicit labels). So if you want those labels to show, the file has to be m4a. If you want to use mp3s it for that special device, then the labels will not be displayed on that version/type of the file.

The ID3 writing program I used is call Kid3 (it's free). From there, I add a new frame called "rtng" (short for rating). For the text, you can input one of the following: "0" for songs with no profanity to begin with, "2" for clean versions of explicit songs, or "4" for explicit songs. Nice thing about this program is that you don't have to re-open/re-import the new song file in iTunes because the program updates the existing file (but remember to save!!!). Just open something else up in iTunes and then reopen where the song is located and it should have the new label on it.