You poor 'merkins. Looks like I will have to educate you (again)
The four coloured buttons are for Teletext favourites. Teletext is a text over TV signal that displays text on your TV screen. The most useful thing Teletext does is closed captions (CC) so deaf people can read what is going on. You can also get weather, news, horse racing, sport results, TV programs and so on.
The US video signal (NTSC) does not support Teletext so don't even bother. Only the PAL video signal (mainly Europe and Australia) supports Teletext. What you can do is to program each coloured button to remember a specific teletext page (there are hundreds of pages).
As to using the buttons to do other useful work you would need to hack into the IR drivers for the remote and find out what keycode each button produces. It must be possible because that is all the Teletext application does. It just understands that when it sees this keycode from the remote it needs to decode what ever page is associated with the button from the Teletext data stream.