First copy them to a new folder under Data/Textures Then in the CK go to "Miscellaneous/TextureSet" and create a new texture set usuing your textures (diffuse and normal) Afterwards go to "Miscellaneous/LandTexture" and create a new Land texture using your texture set.
Now you can use the texture in the Landscape editor. Keep in mind that there is a bug in the Landscape Editpr that makes the first texture in the list always paint as "Default" so give your new Land Texture a name that puts it below "LBlackreachDirt" or you have to sort by filename to be able to use your texture.
It's organized differently. Just one place where texture files are selected. Makes it easier to search for textures with text that needs to be localized.