[Klemm]

Create a new texture with higher resolution and put it in a mods subfolder with the same name and folder structure as the old texture?
Upscaling old textures just doesn't cut it.
You need the ViewIMF-V1_0.exe, which i don't know anymore where i got it from. Then you can extract the sfs archieves with the sfs extractor and open the old textures with the IMFViewer, save them to something editable and edit them with the image manipulation program of your choice.
I don't know if that answered your question, you've got to ask more precisely.