Finally got to writing some sample code for the compass, based off of the Adafruit Arduino library (git repo here), and I've gotten the whole setup working. Now I just have to fix it up, streamline it, and then test it on an attiny. I've included some images of it working below. The first image shows the measured magnetic north and the second image shows the magnet I used for testing in the bottom left corner. Once I figure out the components/footprints I'll be using (mcu package, battery holder, etc), I plan on doing the board layout next.