how to get white/black items

No, its not the mods that make the colors, silly, its done by changing the unique's name to another unique's name, so that the game makes the palette shift for that unique.

For example, making a "Swordguard Spired Helm" would make a white helm, because the Swordguard sword has a white palette shift. Thats the method for making white items.

Now, if you wanted an orange item, you could make it a "The Grandfather Spired Helm." If you wanted a black item, you'd make a "Corpsemourn" one. If you wanted a red item, you could make it "Blade of Ali-Baba." Etc.