download it
go to coolshoes.moxvallix.com/
click on editor if you're not already there
press import from computer
select this base
go back and select your skin as well or the skin you'd like to edit
move the outfit over your skin
fix anything unnecessary(like erasing clothing overlay from your current skin!)
download
go to the pmc editor and open the skin as an alex template
then download and you're done!(the pmc editor is just because needcoolshoes does NOT work w alex template skins)

you can also photoshop it over your skins but ive never done that so cant give instructions on it !