The engineers manual can be found online.
Service mode can be accessed by users and engineers,, when entering engineers code select programming in the first instance.
I prefer the by code method (as you can copy the code put everything in place and add using the code and do a walk test afterwards), but that can only be done if you can see the code on the device to add. Also the CS software would allow you to put the codes in and add them all in one go.
The manual which I found online in seconds tells you the different methods and how to access each one.
It also tells you how to learn the device onif activating the device to do so.