Here is the conf file for the dutch NOS teletext

WARNING! This is still work in progress

to change this put it in the n900 memory and do as follows:
1. install rootsh (to become root)
2. install dexter from repository
3. extract and copy file in this attachment to the n900 sd memorycard from pc
4. reboot n900
5. open xterminal
6. typ "sudo gainroot" [enter]
7. typ "cp /media/mmc1/dexter.conf /home/user/.config/Dexter/dexter.conf" [enter]

Now open dexter and you can use the dutch teletext