Fairly simple, just download and launch Livesplit.
RIght-click the timer and choose "Edit Splits". After you enter the Game Name, the text stating "There is no load remover for this game" will change. There'll be a button to activate the load remover, do so, and click the OK button. Any other settings are up to you, and won't be covered here.
That's only the first part though, it still won't function properly without the next step.
Next, right-click the timer and choose "Edit Layout". Double-click "Splits" and scroll all the way down to the "Timing Method" field and choose Game Time.
Lastly, choose the "Timer" tab and ensure the "Timing Method" field is set to Game Time. Apart from personal changes to settings, you can now click OK and go speedrun across the Old World and the New World.
As you probably already know, Immortal Empires is coming on August 23rd. I plan to have the board ready by then, though we (as the moderation team) cannot say, if speedruns will be accepted immediately after release, not knowing the technical state of the campaign (also, the amount of game breaking
