Actually, it's spelled "crosshairs".
It's weird that you're asking this, since the MP58 natively comes with those dynamic crosshairs.
Because of that I'm afraid I can't help you, but I guess I can show you the readme.
Quote: "Instruction: How to change dynamic crosshair to static crosshair and vice versa.
Open folder of any weapon, in which you want to change the crosshair, and then you will see two folders: Dynamic Crosshair and Static Crosshair. If you want to change dynamic crosshair to static, just open Static Crosshair folder, copy the entire contents of it and paste into the main folder of the weapon. Perform the same action if you decide to change the crosshair from static to
dynamic, but you will need to copy contents from Static Crosshair folder this time.
Notice: Some weapons such as: Grenade, Knife, Panzerfaust, Panzerschreck and Stielhandgranate don't use crosshair, therefore, you won't find these folders there."
Offtopic : Ordering MP58 is a misplaced buy IMHO, the n°68 is basically the same but with the addition of a large variety of characters.
"I like to keep this handy, for close encounters."