Actually it is possible, but only if you use 3rd party tool.
ESO Launcher has option "EnableProtectedLuaFunctions" which is disabled by default. If you enable it in settings, you can call private and protected functions.
From Settings.ini:
Code:
[General]
# This setting, when set to true, allows player created mods to use protected or
# private Lua functions such as: SendChatMessage, ToggleMount, PerformAttack, etc.
# If you change this setting, you must restart your game for it to take effect.
#
# This is a GameModi Plus only feature
# default: false
EnableProtectedLuaFunctions=false