Put all these folders into a folder and place that folder in your local \Steam\skins folder.

For example: C:\Program Files (x86)\Steam\skins\dsect-steamskin

Go to steam setting (default: click on steam in the upper left corner then click on settings).

Under "Select the skin you wish Steam to use (requires Steam to restart)" choose the name of the folder you put all the folders in.

Tada! Restart steam and you are good to go.