Successful install on Zyxel NSA-325
Once I've been back through my notes I'll hopefully pull all the detail together, but in essence its enabled by the work done for the Fonz Fun Plug environment which is available as a package on the Zyxel NAS

High level view...
1) Install FFP 0.7 zyxel package (after adding additional Zyxel repository)
2) Add the various FFP site definitions
2) Install ffmpeg/lame via ffp (Slacker util)
3) Install Java
4) Install Serviio
Enjoy decent DLNA server

Many thanks to those that created the various tools (and how-tos etc) to make the above possible !