Acccessing teletext services via home computers - a widely used option open to modern information-seekers - is nothing new. This article describing the renewed interest in the BBC Micro explains how, with an adaptor, it is possible to view Teletext on the system rather than a television - there is a built in mode for teletext.
The teletext mode became quite popular because of its speed, low memory footprint, and suitability for serious (text based) applications, for example teletext information services and bulletin board systems (like Prestel).
And, according to this article, there exists a program with which one can actually program the pages. Whilst I am sure this is not what is generally used to enter the information it was quite a big breakthrough in 1983 when the technology was still less than a decade old.
As a side note, I have subscribed to the Teletext mailing list.
This article is an instruction manual for ITX, a computer program which allows users to view Teletext pages on their computer. They can enter the desired page number into a text field to navigate and can switch between analogue teletext services such as Ceefax and Teletext. It even makes mention of how it can be adapted for a hand-held device, meaning teletext services can be accessed from almost anywhere at a time convenient to the user.