I was able to import the table (I did have to make sure System Objects were displayed), and it took effect after I restarted the database file.
Thanks, @GPGeorge !
Has there been any progress/update on getting the custom ribbon to appear for Northwind 2.4 Developer Edition?
I downloaded the file from the link provided by @GPGeorge to the Features Access Templates, as I was previously experiencing the same OneTimeProcessing error this thread originally...