I don't know a thing about it, but the first thing I would do is google Teletex.

Bill

Do you edit the content of the transport stream that you want to broadcast?

If yes, you just put in the stream with the teletext into the multiplexer, transfer the proper PIDs to the output and couple them with the correct services.

If you already have the TS and you wanna insert the teletext locally, then you need a re-multiplexer for it, just before the modulator. Apart from this everything are the same.