Interesting question… I am also trying to get a handle on the Hermetic concepts within IIH. I more used to oriental modalities with the like of prana, Qi, Chi, Ki etc.
Here is one which might sow something of a comparison, although I would also very much welcome a more plain English summary on Ahasha?
One explanation found: - http://beaskund.helloyou.ws/netnews/bk/soul/soul1028.html
Vivekananda, who did so much to reveal the soul of India to the West, says:
"According to the philosophers of India, the whole universe is composed of two materials, one of which they call Akasha. It is the omnipresent all penetrating existence. Everything that has form, everything that is the result of the compounds, is evolved out of this Akasha. It is the Akasha that becomes the air, that becomes the liquids, that becomes the solids; it is the Akasha that becomes the sun, the earth, the moon, the stars, the comets; it is the Akasha that becomes the body, the animal body, the planets, every form that we see, everything that can be sensed, everything that exists. It itself cannot be perceived; it is so subtle that  it is beyond all ordinary perception; it can only be seen when it has become gross, has taken form. At the beginning of creation there is only this Akasha; at the end of the cycle the solids, the liquids, and the gases all melt into the Akasha again, and the next creation similarly proceeds out of this Akasha.
By what power is this Akasha manufactured into this universe? By the power of Prana. Just as Akasha is the infinite omnipresent material of this universe, so is this Prana the infinite omnipresent manifesting power of this universe. At the beginning and at the end of a cycle everything becomes Akasha, and all the forces that are in the universe resolve back into the Prana; in the next cycle, out of this Prana, is evolved everything that we call energy, everything that we call force. It is the Prana that is manifesting as motion; it is the Prana that is manifesting as gravitation, as magnetism. It is the Prana that is manifesting as the actions of the body, as the nerve currents, as thought force. From thought, down to the lowest physical force, everything is but the manifestation of Prana. The sumtotal of all force in the universe, mental or physical when resolved back to its original state, is called Prana...
- Vivekananda, Swami, Raja Yoga, pp. 29, 30.