There's no patch file, Impulse updates your game files directly. The way to do it would be to update the game (or download the whole thing), then right click it in Impulse and create an archive. Copy the archive to your flash drive (the default archive path can be shown and changed if you click the blue orb > preferences > folders in Impulse) and then use Impulse at home to install from the archive.

Impulse will need to connect on your desktop, but it won't need to download anything so your 28.8 connection should be ok for that.