I've been trying to install the latest Kali on a Winbook tablet (2GB, Atom). I have a 4 port USB hub, with a keyboard, mouse, and install USB. At a certain point, it says I need non-free drivers for the internal Wifi. I put the drivers on a second USB, in the root directory, and a number of subdirectories I created that were supposed to work, but they were never found. I installed 3 other Linux-friendly USB Wifi adapters, but they all asked for non-free drivers. I pushed ahead, then got warnings about not having Internet, not being able to access the repositories. I still pushed ahead. Eventually, Grub fails to install, despite trying repeatedly.
So, how do I install without Internet? Or, how do I install the proper non-free drivers?