...... How does this system tie into the hexagram I ching system, if at all?
First, we need to realize that the hexagram goes back almost 5000 years. It is very old and comes from the days when the sixth element, Seed, existed.
Obviously the six elements and the hexagram are very similar in nature. Hexagram has six lines and each line is Yin or Yang. Just like six elements with a Yin and a Yang meridian.
Now, there is really only one way to view a hexagram according to six-element theory. You have to use trigrams because they have been used since the oldest known records of the I-ching.
The bottom trigram is the Yin triangle of Essence and the upper trigram is the Yang triangle of Essence. In this way, six-element theory would say that a certain configuration of Yang activity is transforming a certain configuration of Yin substance.
In this hexagram, the Yang triangle of Essence is pure Yin. Thus, the lines in the upper trigram correspond to the yin meridians of the Yang Essence, namely of Hand-YIn (Heart, Lung and Pericardium).
These Yin meridians are actually more dynamic than their Yang counterparts (Small Intestine, Large Intestine and San Jiao). If all the lines were solid in the Yang trigram, it would be less dynamic. The Hand-Yang meridians oversee and regulate activity, but the Hand-Yin meridians are more restless, energetic, impulsive and even more prone to panic attacks... (see page 82 of book)
So, even though this Yang Essence trigram is all Yin, it is the most actively dynamic and potentially unstable of all Yang Essence trigrams.