Shannon says they adopted "a really simple, lo-tech approach" to the procedure. His eye was held open, using a forefinger and thumb, as the pigment, which is the exact same type you would use in a regular tattoo, was injected into his eyeball.
"We injected pigment under the top layer of the eye using a syringe, which, to the best of my knowledge, has never been done before, either medically or cosmetically."
(Via Aberrant News.)
Can ink-black "Communion"-style eyes be far behind?