Because demigod maps /bindata and dgdata.zip to the same location Lua placed in /bindata still run at load up. So if you want to load lua at start up you can just place you LUA in the map directory or the heroes directory and it will load it in. Delete it if you want to play online as it prevent games from syncing.
Could you be a little more specific?
What exactly do I have to do, to modify the lobby options?
(I placed my mod in many folders, inside /bindata but it didnt work.)