I was wondering if there was a way to make a KeyBinding require 2 keys, like LShift + S.

Technically I have it working. But in the controls menu it only shows the 's' key because of the way I did it.

 

		KeyBinding[] keys = { new KeyBinding("Skill GUI", Keyboard.KEY_S), };
	boolean[] repeat = { false, false };
	KeyBindingRegistry.registerKeyBinding(new KeyPress(keys, repeat));

	@Override
public void keyDown(EnumSet<TickType> types, KeyBinding kb, boolean tickEnd, boolean isRepeat) {

	pressed = !pressed;

	if (kb.keyCode == Keyboard.KEY_S && Keyboard.isKeyDown(Keyboard.KEY_LSHIFT)) {
		PacketDispatcher.sendPacketToServer(new RequestSkillGUIPacket().makePacket());
	}

}

The way I did it, it does require a LShift + S, that part works.

But like I said, in the controls menu it only registers the "s" key, and since it's already being used by something, it's a 'conflict'.

I hate to say this but it sounds like you're either going to have to create your own control menu(easier) or edit the base control menu class by making a coremod. Those are the only two options I can think of.