According to Apple’s workflow for Final Cut Pro 7, you can import an SCC file and it will print it to tape in the same location as CEA-708 captions and line 21 as well. Although I’ve never done this personally we use MovCaptioner on the Mac to create our SCC files. It’s a low cost alternative to CPC. You can download a demo version of the s/w here: https://www.synchrimedia.com. If you go to their Help page, they have a link to the Apple page I’m referring to. Note this does not create full-fledged 708 captions, but it should be good for broadcast.