Perfect! I even used the Modifiers but ended up saving it as a Standard Function for that's how it seemed to be done everywhere. 
Most prominently here:
Section 3:
This image in the manual:
https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Embedding_Rename_Scripts.htm
And perhaps the explanation of @script in the manual could use a note as well:
https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Command_modifier_reference.htm
Any other similar source I stumbled upon would be older (though relatively new, Opus 11/12) forum posts. So be it.
Thanks!