If I undestood you want to shift characters to the darkside. How? using different new quests or modifing the existent ones? Anyway good luck and keep working.
If you want just skins you can also download skins of the party members in the darkside at pcgamemods, the only problem is that they are static, meaning, just darkside.
Or if what you want is a complete darkside crew, you can download the Sith Armada Mod. Also from pcgamemods.
"Revenge is never a straight line. It's a forest. And like a forest it's easy to lose your way to get lost When engaged in combat, the vanquishing of thine enemy can be the warrior's only concern. This is the first and cardinal rule of combat. Suppress all human emotion and compassion. Kill whoever stands in thy way, even if that be Lord God, or Buddha himself..."