extract the files in 3dtexture.ini. The extraction tool is available in one of the stickies somewhere. Then look for the texture files using the dds converter:

or use a dds converter plugin for your program.
When you find it, convert the dds file into a psd file then use photoshop or GIMP to edit it.
an easier way is to switch the files, so the L1 nix looks like L4 or whatever.
Hope this helps