Icon Theme: apply icon theme from launcher settings, all icons in drawer and home screen will be themed accordingly. Obviously all launchers have this feature.
Icon Picker: change home screen icon one by one manually and individually, pick one icon from theme and replace.
ADW.Launcher and Holo Launcher icon picker are not compatible with my theme application now. Hope this can be fixed in the near future.
For GO Launcher Ex icon mask compatibility problem, see here.