Scripts stuff is very easy.
There are 20 functions, with 100 script commands each, labelled ProcessCommandsXXXToYYY (ex.: ProcessCommands0To99.
There are multiple files in our code in /Scripts/Commands/ for each category.
To find where a specific command is just divide it's id by 100 and go to the appropriate function.
For example, COMMAND_GET_CHAR_ARMOUR is 1245, so it's in ProcessCommands1200To1299, and the command should be added to Character.cpp with the appropriate REGISTER_COMMAND_HANDLER call.