TL;DR:
Use these directions to install to a USB stick, then just load splat.sh (https://git.io/vPHZ0) and run it to install to eMMC.
You get the default ALARM user accounts. (root/root and alarm/alarm).
NOTE
This is a fork of Max Glenister's work for playing around. For latest versions, questions etc. have a look at his repo, solved issues and wiki at https://github.com/omgmog/archarm-usb-hp-chromebook-11
This repo also integrates my fork/snapshot/copy of @starkers method. (splat.sh) which is based off the steps here: http://archlinuxarm.org/platforms/armv7/samsung/samsung-chromebook
The post-install-script is heavily tailored to my personal preferences.
To use this script
On your Chromebook with Developer Mode enabled:
sudo su -
cd /tmp
wget https://raw.githubusercontent.com/wamserma/archarm-usb-hp-chromebook-11/master/install.sh -O install.sh
bash install.sh "/dev/sda"
NOTE: This needs to be run with /bin/bash, not /bin/sh, which is ash.
After you've made a USB stick and booted from it, you can download and run Starkers' splat.sh and install to /dev/mmcblk0 (the eMMC) for a much nicer/faster Arch experience.
Log in as the root user which was created during the install process. Then, select which wifi network to join:
wifi-menu mlan0
Then, download and run the install script, but this time on the internal storage:
pacman -Syy wget
wget https://git.io/vPHZ0 -O splat.sh
chmod +x splat.sh
./splat.sh /dev/mmcblk0
(there should not be any need for running dev_install and emerge parted)