If you just want the easiest working setup: Download the (requires registration, no CD key needed? – actually they ask for a valid key but have a keygen? No – best to use a legit key). Or use GameRanger + your own Warcraft III install.
If you have old version 1.26, GameRanger is the easiest. Install the client, log in, and host a "Warcraft III The Frozen Throne" room. Players join via virtual LAN. Dota 1 Warcraft 3 Download