Are you asking if it's possible to crack the sky network open? In short - no. I've never known anyone who's personally managed to crack open sky, and if there is a weakness in the encryption somewhere it's most certainly not in the public domain like the normal WEP / WPA cracking tutorials.
I have heard people say they've known people with cryptography PhDs and very specialised equipment who have done it, but whether there's any truth in this I don't know. I certainly wouldn't have a clue where to start and I wouldn't say I was a complete encryption numpty. People may have done it, but it's not something you can just spend £10 on then get free sky for the rest of eternity. And if you need to ask the question on here, I'm afraid it's definitely not something you'll be able to do!