I have installed everything from Blaizzen's latest "Release.zip" and followed his instructions carefully.
It seems to work, I have to test it on a real trip tomorrow. At least I heard a first announcement of espeak... Splendid!
Also, the speech server seems to be using almost no CPU when running idle, which is nice.

One thing was odd:
The POI button toggles POI displaying. But: after changing to "All" in settings, it took about 10 minutes until "all" categories of POI appeared (instead of just the preselected subset).
While this long time, the Maps app was fully responsive. Bug or feature?

Thanks for this megacool hack.