This is the answer I was looking for, thank you.
However, in the end Moodle still doesn't know how to properly serve pre-compressed .js.gz files (and likely others). I ended up having to add extra conditions to /lib/filelib.php in order to accommodate. The "content-type" header was wrong, and the "content-encoding" header was missing completely.
Anyway, our SCORM course works now. Thanks for all the help!