$ chdist -aarmhf create landing-022-armhf
Now edit /home/cjwatson/.chdist/landing-022-armhf/etc/apt/sources.list
Run chdist apt-get landing-022-armhf update
And enjoy.
$ cat >.chdist/landing-022-armhf/etc/apt/sources.list
deb [trusted=yes] http://ppa.launchpad.net/ci-train-ppa-service/landing-022/ubuntu wily main
deb-src [trusted=yes] http://ppa.launchpad.net/ci-train-ppa-service/landing-022/ubuntu wily main
deb http://ports.ubuntu.com/ubuntu-ports wily main restricted universe multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports wily main restricted universe multiverse
deb http://ports.ubuntu.com/ubuntu-ports wily-security main restricted universe multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports wily-security main restricted universe multiverse
deb http://ports.ubuntu.com/ubuntu-ports wily-updates main restricted universe multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports wily-updates main restricted universe multiverse
deb http://ports.ubuntu.com/ubuntu-ports wily-proposed main restricted universe multiverse
deb-src http://ports.ubuntu.com/ubuntu-ports wily-proposed main restricted universe multiverse
$ sed -i '/ Architecture /s/.*/& Architectures {"armhf";};/' .chdist/landing-022-armhf/etc/apt/apt.conf
$ chdist apt-get landing-022-armhf update
...
$ chdist apt-get landing-022-armhf build-dep unity-scope-click