You would have to create a new race, called nords, they would be identical to people in everyway, but you would change the bit where it says scale to say 1.2 or whatever. Like the previous posts said look into how to add a new race, once you've added the race you will have to apply it to every nord troop in module_troops, you just add tf_nord (or whatever you've titled your new race in header_troops) to every nord troop.