@alonewolfx2 attached some code in this thread, which I managed to get to compile by making changes to the delay function ( looks like a SDK version issue)
However I have not had time to test it with a device yet.
I also notice that since I posted, that Lua for esp8266 source code has been released on GitHub, which also includes source for the 18S20.
Hopefully I should get time over Christmas to wire up a probe and test the code
Thanks
Roger