Use datasets.at
image repository.
imgadm sources -a http://datasets.at/
imgadm sources -d https://images.joyent.com
imgadm update
This guide assumes you have a working SmartOS setup with your storage zpool(s) imported.
This guide is based on this gist: https://gist.github.com/dreamcat4/f19580cbd31d8f628aca.
Find the latest FreeBSD image, in this case d20b8738-7a2a-11e4-bea0-83cb697e6c7c (freebsd-10, 20141202).