First get the source code:

mkdir brillo
cd brillo
repo init -u git://github.com/ED6E0F17/brillo_device_raspberrypi.git -m manifest.xml
repo sync

For ArmV6 builds, disable some inline thumb2 code:

rm system/extras/tests/memtest/Android.mk

Building Brillo uses the Android build system:

repo sync
. build/envsetup.sh 
lunch
make -j3

Lunch options:

liz:  armv6 (PiZero).
gert: armv6 (ModelB+).
eben: armv7 (Model2B).

Static IP addresses:

set in common/init.net-setup.sh
eth0 192.168.1.10
usb0 10.10.10.10