Install on USB stick

Format the USB stick. For example

sudo mkfs.ext4 -F /dev/sdb

Mount it

sudo mount /dev/sdb /mnt

Unpack the roots

cd /mnt
sudo tar xfJ ~/archxo-1.tar.xz

Unmount the stick

sudo umount /dev/sdb

Finally plug in the stick and start the XO.

Build a rootfs

This will include only the packages which are essential to boot, configure wifi and install packages.

pacstrap -d /rootfs systemd systemd-sysvcompat pacman netctl \
    wpa_supplicant dialog linux-firmware grep dhcpcd