just drop the file into
C:\Users\Documents\Bioware\Dragon Age\packages\core\override and you are done

Make sure to download
http://www.nexusmods.com/dragonage/mods/4450/?tab=2&navtag=http%3A%2F%2Fwww.nexusmods.com%2Fdragonage%2Fajax%2Fmodfiles%2F%3Fid%3D4450&pUp=1

under optional files select

DA_Inquisition Hairstyles by Risibisi