There is not much you can do except use an editor to change some values and cheat. Communism is an option, but cuts production everywhere and requires a police station and courthouse in every production city.
For building a Forbidden Palace more than 12 squares from the capital (standard map), the only way to go is to use a leader to hurry production. Otherwise your Forbidden Palace will be completed by the time the game is decided. There is no other way to hurry a Forbidden Palace, other than a leader. For other outlying cities, you can rush buy improvements, cut down forests, or disband units to build stuff, but these techniques will not help for wonders or a Forbidden Palace.
To get a leader you have to fight a lot and preserve your elite units. Good luck.