I was following the instruction to install the latest snapshot everything went fine until I came to update opkg and install luci
If you are updating over a lan as I suspect most will be, messing about with changing the router IP can be a problem for the unwary.(like me 
)
Far easier is to change the routers IP from static to dchp it will then connect to your network and reach the 'net.
After that you can use the serial console to download luci
Then go to your home network router's page and find the IP of the router you are configuring,
You can then log in and configure your router using luci over any browser using the IP you found
The commands are
uci set network.lan.proto='dhcp' which sets it to dhcp
and
uci set network.lan.proto='static' to set it back to static for when you come to use it for real
Hope this helps someone, it worked for me.
if people approve it might be good to doc this as a note on the instructions