I have a complicated problem. My Xbox doesn't connect to the Internet cause we were routing it through the PC but the adapter died and the new one we got wont bridge. This happened a week before the update came out and I know I can update my Xbox by downloading the update off the Internet on my computer but can I do that with the minecraft update.
I think you'll just have to find an adaptor that will enable you to re-establish your XBox's connection to XBox Live. As MG stated, the only way to download the update legitimately is through XBox Live. From Microsoft's point of view - their computers verify your purchase of the original game via your Live account matched to the identification of your particular console.
Only the dashboard update can be downloaded from a PC and put on your console.