Replacing Start Point (AI)

[Animalpower]

I need a trigger or something to replace the building at start point. In my map all players are human, and I want to replace the Town Hall with my own created building. I need also to replace the Peasants into other unit, example: Gatherer. In my map, to defeat the player, the city center building (start point) must be destroyed. I want that AI works, like in Melee Custom Maps, and that I can upgrade the main building.

 

[blacksheepwalll]

what happens if you modify the normal starting buildings for the melee trigger