There's no patch file to download. Impulse checks your files versus the updated files, and downloads those that are changed so you get only what you need. Once you register Sins so that it shows up under My Games, it should show a yellow (!) icon with the available update. Then you just click the Sins icon, and in the lower right hand corner instead of the normal "Run", it will have "Update". Clicky, and Impulse will do the rest.
