Meh, I'll go for the easiest way to do it.
1. Create a shortcut to the Soldat .exe file somewhere.
2. Right-click the shortcut.
3. In "Target", add "-mod [NAME OF THE MOD DIRECTORY]" without the quotes to the existing text there.
If you don't know how to prevent replacing the original Soldat assets, it's done by extracting a mod to Soldat\Mods\Name_Of_Mod and then running the very same Soldat.exe with "-mod Name_Of_Mod".
I hope you understood me, just ask again if there's something you don't understand about my Swenglish.