I can't make any statements which provide exact guidelines on what is and isn't ok as things are still evolving. Currently, we don't plan to help or hinder mods exclusively created for and used in offline mode. In online mode, anything that depends on or reacts to the current game state is strictly forbidden.
So for example, using num lock to auto cast a skill is ok. Nothing was done to alter the game client, the OS doesn't have any idea what is going on in the game and is just spamming a button over and over as though you glued the key down.
As a counter example, something which waited until your health dropped below 10% and then auto-logged you out would not be ok as that depends on and reacts to the state of the game.
I like to think of it like if I could get a handful of materials from a summer camp arts and crafts hut to make this happen on my keyboard, then it's probably ok.
This is far from an exhaustive explanation and it can change at any point. We try to be reasonable with things like this and judge each situation in its entirety before taking any sort of action. If you have a specific thing you would like to do but aren't sure if it's ok or not, please contact support directly with details.