To install skins put the three folders into DCS World/Bazar/Liveseries/C-130 folder.

OBS! You also have to add the line "cnt_unit( units.Planes.Plane, "C-130");" under the line "local units = country:get("SWEDEN").Units" inside db_countries script. 
Which you find in DCS World/Scripts/Database. This enables the C-130 for Sweden. Might not work with 2.5 but otherwise they are enabled for USA.
You can also add countries in the description.lua

Hope you ENJOY!