1)
# cd /usr/src
# make packages
2)
# make PKG_CMD=/usr/local/sbin/pkg-static packages
3)
(making sure that nothing is still using 'pkg' when the override is in place)
# cp /usr/local/sbin/{pkg,pkg-dynamic}
# cat /dev/null > /usr/local/sbin/pkg
# make PKG_CMD=/usr/local/sbin/pkg-dynamic packages