Apparently not, I thought the same as you but I heard that the usb port on the back of the sky box is for future use I think.
But saying that I think I have heard of a web site that that will do this for you but have also heard that your laptops hard drive could get damaged
I havent really been of much help here have I but I am almost sure that you cant.
I used to be indecisive but not sure now.