With the video terminal,you need to select AUX-2,for the Scart socket,and AUX-3,for the 6 pin din input.Both inputs have control pins,for priority switching.Connect the cable box to the Scart socket,but if you can disable "Scart control"in the box set up menu,it means the cable box can't override other sources,such as tv or game unit connnected to the Din.If you can't disable the Scart control via the setup,dismantle one of the Scart plugs,and cut the wire to Pin 8.
Great tellies these,I've got four (men in white coats are coming to take me away,ha ha,hee hee!)
Nick