In this guide I will show you how to set up an Onion Pi that you connect to the ethernet port on your computer instead of setting up a wireless access point. We will be using Wi-Fi for our source network connection, but you can use a USB ethernet cable if you want to with some modifications (change wlanX to ethX). When you connect a network cable from your computer to the Raspberry Pi, you will receive an IP address from the DHCP server and all your traffic will be routed through the TOR network.
I have been using the following sources with some modifications to make this work:
https://learn.adafruit.com/setting-up-a-raspberry-pi-as-a-wifi-access-point/
https://gist.github.com/superjamie/ac55b6d2c080582a3e64
https://learn.adafruit.com/onion-pi/install-tor