Women are heaven;
women are Dharma;
and women are the highest penance.
Women are Buddha;
women are the Sangha;
and women are the perfection of Wisdom.
—'Chandamaharoshana' Ch.8 v.30
What the Yoni Tantra actually teaches is that women must be treated with respect. This quote from the referenced source (The Scarlet Letter) is related to Buddhism.
At the time I found it (December 18, 2004), I could find no other reference to the Chandamaharoshana.
Today the best reference is at Keith Dowman's website.
Chandamaharoshana is the consort of Acala, one of the Five Wisdom Kings of Vajrayana Buddhism. Wisdom Kings are guardians of Buddhism.
According to the Wikipedia entry for Acala, "Acala is said to be a powerful deity who protects All the Living (sattva, shujō (衆生?)) by burning away all impediments (antar-aya, shōnan (障難?)) and defilements, thus aiding them towards enlightenment."
Shujo refers to all sentient beings.
Shonan refers to "difficult obstacles" to Enlightenment such as evil karma accumulated in a Buddhist's life.
Even though Chandamaharoshana appears to be associated with tantric sex, this is a highly respected form of mindful practice.
In tantric sex, you have the tantric devotee (usually male) and the tantrika (the woman representing the female consort) perform according to the Chandamaharoshana Sutra.
Included in all of this are days of fasting before the day of tantric initiations, and also the gifts mentioned in the sutra must be presented to the tantrika.
As well, the devotee must study in tantric yoga with a master, though the tantrika may also provide this service if a master is not immediately available.
However, the purpose of tantric sex is not the sex itself but the experience of the spiritual "energies" of Shiva and Shakti.
According to Lama Thubten Yeshe, "...each one of us is a union of all universal energy. Everything that we need in order to be complete is within us right at this very moment. It is simply a matter of being able to recognize it. This is the tantric approach."
Thus it is possible to view tantric sex as mindful practice.
More importantly the Chandamaharoshana Sutra also has figurative meaning in the symbolic sense.
Thus it's not about sex; it's about respect for man and woman within a religious context.
The Scarlet Letter | v2n4 | "The Yoni Tantra, Part I": http://www.scarletwoman.org/scarletletter/v2n4/v2n4_yoni1.html