Cat's UV Flip
This MilkShape plugin flips the UV map of selected vertices, either horizontally or vertically, as shown in the example below.
Download, unzip, and put the file(s) in your MilkShape folder.
You will have new options in the Vertex menu:
Cat's UV Flip (horizontal) and Cat's UV Flip (vertical)
In the MilkShape groups tab, select the group whose UV mapping you want to adjust.
Press CTRL-T to show the UV mapping window. In the UV mapping window, select
the vertices whose UV coordinates you wish to flip. You can also select vertices right
in the meshing window, without opening the UV mapping window, if you wish.
However, it is better to work in the UV mapping window, so you can see the map.
In the Vertex menu, select Cat's UV Flip (horizontal) or Cat's UV Flip (vertical).