There are two ways. You could drag its contents into your Soldat folder directly and permanently modify it, or you could put it in ..\Soldat\Mods and use an altered shortcut to operate it. For this temporary way (as you can flip between the default and other mods), make a shortcut of Soldat.exe, right-click it and select Properties, and find the Target line. Behind it, place without brackets [ -mod X] at the very end of it (do not forget the space in the front), and call X the name of the folder in \Mods (It can't have spaces).
There's also a third method similar to the second but that uses batch files, which I have no clue how to work
