Is it possible to make selenium use the TOR browser? Does anyone have any code they could copy-paste?
I looked into this, and unless I'm mistaken, on face value it's not possible.
The reason this cannot be done is because:

Tor Browser is based on the Firefox code.
Tor Browser has specific patches to the Firefox code to prevent external applications communicating with the Tor Browser (including blocking the Components.Interfaces library). 
The Selenium Firefox WebDriver communicates with the browser through Javascript libraries that are, as aforementioned, blocked by Tor Browser.

This is presumably so no-one outside of the Tor Browser either on your box or over the internet knows about your browsing.
Your alternatives are:

Use a Tor proxy through Firefox instead of the Tor Browser (see the link in the comments of the question).
Rebuild the Firefox source code with the Tor Browser patches excluding those that prevent external communication with Tor Browser.

I suggest the former.
Open tor browser with selenium