The most complete description of an Inchoroi I could find/remember was from The False Sun, below:
The creature stood naked, as was his want, his wings folded into wicked hooks about either side of his great skull, which would have been cumbersome, had it not curved into a crest, narrow and deep, like an oyster set on end. A proportionate face hung from the fore, loutish with the absence of expression, nostrils drawn into shining gashes, sockets plugged with lobes of bare white meat. A second face filled the mouth, sheathing a second skull fused within the crocodilian jaws of the greater. Second eyes regarded the Hero-Mage with leering expectation. Second lips grinned about teeth like nails..
I feel like there are more descriptions of them somewhere (other than the back of TWP, which doesn't really add much to the above). Anyway, that's what's so great, and frustrating, about the Inchies. Very specific, sometimes contradictory, descriptions and they remain an enigma to the imagination (at least to mine).