Larian Studios Forums Divinity - Original Sin Divinity Original Sin - Mods Can I change existing skills properties?

So I take it I can't just edit the skilldata.txt in C:\Program Files (x86)\Steam\SteamApps\common\Divinity - Original Sin\Data\Editor\Templates\Stats\Generated\Data ?
Do I have to copy all that and make a new mod or something? How do I go about doing that?