Take it from me, you CANNOT access websites that bypasses any Router/Proxy Server in a works environment that connects you to the Internet - It's like saying I'm getting my electricity from next door even though I'm not connected to their mains. Physically impossible.
Ian, its gonna be something completely stupid, like connect to the wireless network of someone down the street. Clearly no-one can access websites on a works pc, without actually going through the network.
However, i have to disagree with you about the electricity. i get mine from a satellite... well, ok, its not really a satellite, its a pringles tube. Anyway, cant say any more. Its all hush hush