Dear Jeff,
We have a barcode application (in Adobe CF, not yet in Lucee) that has to produce several hundred thousand barcodes and then merge them into PDFs. We use cfdocument for the merge portion but not the actual generation. We looked into the custom font approach but it seemed clunky.
Instead, we use barcode4j -
http://barcode4j.sourceforge.net/ - a simple Java app that you can drop into tomcat and run as a service. I can't recommend it enough and the developer was helpful on a couple issues (at least, four years ago, when we did it).
I don't anticipate any changes in how it would work under Lucee since all CF has to do is make the web request to the service.
Good luck!
Sam