Audio features into custom mp3 fields

[LouWeed]

Hi, thanks for all the effort!
Is it possible to enter audio features values into custom mp3 tags created in Mediamonkey (MM) for example?
To be more clear: i would like to enter five audio feature values into the five custom fields created into MM for this purpose.
Eg: to have the danceability value shown in MM Custom Field 1.

It is my understanding that MM uses the COMMENT frame, each time with a unique description (Songs-DB_Custom1, Songs-DB_Custom2, etc) to indicate which custom field the data belongs to.
However in onetagger there is only the option to enter frame and not description when selecting in the properties. I've tried "COMM Songs-DB_Custom1", "COMM:Songs-DB_Custom1", "COMM=Songs-DB_Custom1" but it doesn't work.

Is there any syntax that will do the trick or is this option not available? If not, could it be added in a future release?