Just been through this job recently and I can tell you that it is sometimes possible to get the cables out without a diagnostic. Basically ours won't talk to the handbrake module for whatever reason but it does operate on the switch (it's under investigation) so what we had to do was turn on the ignition, press the brake pedal 3 times fully and hold down on the 3rd time, then press the brake switch down 3 times and hold down on the 3rd. The box then winds the cable out slightly.
Once you've done this, I'm fairly sure the car thinks it's in the shoe mounting position so that's all it will do. If you want more cable, you need to disconnect the battery, what a few minutes, reconnect it and do it again. 6 times seemed to be the magic number for us.
When you fit the new shoes, make sure your parking brake cable hasn't fallen out of the holder on the offside because of the way it sits in the drum or your EPB may wind itself too far in. Ask me how I know! We used a tiny cable tie on the cable holder to keep it in place until there is tension on it.