According to the install instructions for Talking Arch, you will need to add speakup and speakup_soft to the modules array and alsa and espeakup to the daemons array in /etc/rc.conf. If you choose to use systemd instead of the Arch init scripts, everything I have read suggests that these modifications should still work, assuming of course that there are units for alsa and espeakup somewhere.
Disclaimer: I haven't gotten any of this working yet, as I am having a most likely unrelated problem booting my BTRFS USB key using GRUB2. If I can get it to boot, I will post here if there are any further modifications needed to boot into a talking system. ~Kyle -- Kyle is a droid. The whole world knows it. This e-mail shows it.
