"The Sixty-Four Arts," a body of teachings that speak to what every lover should know, are referred to in the » Kama Sutra and Ananga Ranga of India, The Perfumed Garden of Persia and the Pillow Books of China and Japan. In Tantric, or Vajrayana, Buddhism as practiced in Tibet, the Sixty-Four Arts are used to further spiritual development. This process views ecstatic orgasm as a vehicle to subtle and powerful levels of consciousness that can reveal the nature of reality -- and thus release us from craving.
There are really no "techniques" in Tantra besides cultivating awareness and presence. Rather than renouncing pleasure, Tantra uses everything in life, including sexual pleasure, as an avenue for exploring the profound nature of consciousness.
Accordingly sexual positions are there to increase the ecstasy of the practicioners so that they can dissolve into the ultimate extasy of joy. Every position is to stimulate the senses and to increase the pleasure one feels about his human form and surroundings. By embracing the sensual stimulus arising from the unity of human forms, one is able to transcend their physical reality and open up to transcendential dimensions of divine unity.
By no means should any kind orgasm be controlled forcedly, but all sexual ecstasy must be let to flow free and spontaneously. The control of ejaculation of semen and simultaneous orgasm shall arise automatically with practice.
