I guess you mean to watch non-Freeview (encrypted subscription) programmes?
Contrary to what 'The Man in the Pub' may tell you it can't be done.
To do it, your box would need a Conditional Access decoder (which it doesn't have), some kind of viewing card slot (which it doesn't have) and some kind of 'magic' viewing card (which I am willing to bet you don't have).
t, March 2008