Importing initial data to populate the custom values dropdown

The new custom value dropdown boxes, new in 318, are an amazing addition, thank you. I'd like to populate some of them with some initial values (record labels, style, mood, artist, comment, as examples) that I use on a regular basis. Adding values one at a time is very tedious and I would like to import these values from a text file. Is this possible? I found a .dll file that contained the individual values I entered initially to check out the new feature. I successfully edited the file and indeed did populate some of the dropdowns, but ran into what seems to be limitations as to the number of entries I can add. If no current import function is available could you expound on the criteria/specs for the fields available.
Thanks

You could start reading here, it should help you to get the idea:

Step-by-Step with open source tools: