Peruse the Telestream MacCaption website for more info. Teletext is not the same as EIA 608/708 closed captions. You will have to re-encode your original closed caption files from 29.97 to 25 fps, and then find an application like MacCaption to imbed the caption stream into the exported video master file. I don't think this works like a tape export. What you may end up doing is accompanying the program source file with a .scc, .cap or other file.
"I always pass on free advice -- its never of any use to me" Oscar Wilde.