For this Tutorial You need:
S4CAS Tools by Cmar (You could also use Sims4Studio but for overrides I find this easier since you can clone multiple colour swatches at once)
s4pe by Kuree
Side Note: If you want to merge various packages you made, use Sims4Studio instead of s4pe
Hopefully this tutorial is helpful, if you have any questions let me know, I’d be happy to help :)