I believe in TWP in the scene where Kellhus "whelms" Serwe to find out what the kell-skinspy had asked her, the whelming is described as the place where voice overwrites voice, or words to that affect. sorry i dont have the book handy to check. "He slowly scraped the event from the parchment of her soul" or something like that. I believe Kellhus also called a different ceremony the whelming or the like, where splash oil on the face it goes on fire and a priest with a wet cloth puts it out. Which is much more ceremonial.
It also seems very familiar with the state Inri was trying to invoke in little Kel before(we think but maybe actually after, not before) he was "saved" by the cleaning dude pulling him back, they are even induced in the same way, by matching heartbeat and breaths. The voice warns Kel, "he breaths as you do..."