Turns out to be pretty simple.
- Install ushare. There is a ushare and libdlna package to install
- Edit the config file in /etc/ushare.conf. Set USHARE_ENABLE_XBOX, USHARE_DIR and USHARE_IFACE
- Restart with /etc/init.d/ushare restart
You don't need to add any routes that they recommend (as long as your default route is OK and you're only using one network interface). Remember to set the appropriate interface (in my case my wireless is eth1) as the USHARE_IFACE option.
The default config file in 1.1a had invalid config item names. All config items should start with USHARE_. The Xbox one did not in my default config file.