Try this (link may expire if unused for a while).
All you need to do is unpack a 1.21 WorldEdit executable into your WC3 installation directory (not sure if it comes with one in the bin folder, remember to backup the existing one so you can always restore it for future updates of the game) and it should work.
All you need to do is unpack a 1.21 WorldEdit executable into your WC3 installation directory (not sure if it comes with one in the bin folder, remember to backup the existing one so you can always restore it for future updates of the game) and it should work.