Japanese Black Pine can stand a good amount of shaping or can be grown in a sunken container to keep it root bound and small in scale. Azaleas and camellias are both important factors. Dwarf Bamboo and Golden Bamboo can be widely used, and Heavenly Bamboo can be used for accent. Flowering Cherries and deciduous Magnolias should be definitely included. Taller trees that fit the oriental scheme are Gingko and Sweet Gum.
Experiment is what it takes -with plants and with rock and water.
Your garden may not rival the Emperor's Palace but it will be pleasant nonetheless.