I think that's not possible on DVB-T (yes, there are countries like mine where DVB-T is used with Teletext). I wonder what are the options to recover teletext from today digital TV.
A standard dvb dongle with tsduck to extract specifically the teletext pid should do the trick.
You can also use tsduck and hides modulator to inject your own teletext to your tv. Or you could use it to inject a HbbTV web page and do whatever you want. Like including a teletext JS emulator.