Running a beets plugin on files outside of the library

Is it possible to run a beets plugin on files that are not in the library? I have files that I do not want to put in my library because I want a clean one format library without file corruption. Re-ripping my library is taking forever, so in the meantime, I wish to listen to both sets of files. The problem is, my old collection has different replaygain settings. It would be so easy to run the beets replaygain plugin on my old files to correct the volume difference.

Is there a way to do this?

That’s not currently possible; sorry! An alternative might be to temporarily swap your library config option to point to a different database file, and then delete that when you’re done.