Adding mipmaps to Blueprint KDTW

Hello-I had read that you could add mipmaps to KDTW texture files to help reduce the shimmering. The instructions were to use the imagetool in the SDK and opening the texture files in the Blueprint KDTW folder and adding mipmaps. When I try "adding mipmaps", a dialogue box opens that asks me to choose a file, even though I already have a texture file open. If I choose the same file again, I get a dialogue box that says the mipmaps are a different size. Any thoughts?--Don