see as other men's see.  He would not know of them before he grew 
to be an old man, but in time, he would know them all and more; 

Is this contradicting itself, or am I just too tired?
("he would not know ... but in time he would know")

had come.  He would even dare, though only once, to stand outside 
the colossal walls of dread Thalarion and listen to the laughter 
of spectral Lathi as it came drifting from within, but even he 
was not so brave (or some might say foolish) as to step inside 
that cursed place.

One too many "even" in that sentence, IMO.

    In time, he would come to know many of the delights that the
Dreamlands had to offer, and no few of the horrors as well.  He
would be one of the few men to hear the voice of the Black Siren
and not have his skin line the walls or floor of her pit.  And 
while he never looked upon the throne of Azathoth as it is said
Kuranes once did, he did once glimpse the Basalt Pillars of the 
West from his perch in the crows-nest of a trading ship of 
glorious Celephais, and see for a moment how all the oceans of 
the Dreamlands pour off into that sear gulf of unlawful space  
which lies hungry and waiting beyond to devour it.

You're sorta shifting tense here, from future to past.
("And while he would not look upon, ..., he would once" etc)

    Where it all began, though, was in the kitchen of a small

IMO, "The place where it all begin"

Chinese restaurant, the Nekohanten by name.  Ranma had gone there
for aid with an affliction of the mind.  A long-ago incident of
his childhood, brought on by a feckless father's imbecilic 
actions, had left him with a severe phobia of all things feline.
That in itself would be bad enough, but with sufficient exposure,

would have been

    The complexities of Ranma's personal life need not be 
explained here; the details of that alone have filled volumes.  

Some 38 or so of them, eh? :-)

    Thus he found himself that day in the Nekohanten speaking
to the aged proprietor, a woman renowned for her wisdom of the
eldritch lores and judgement in applying them, if no longer for 
her beauty.  And so began a grand and terrifying adventure, into 
a realm of nightmares and dreams, gods and monsters, beyond the 
veil of sleep.

I must comment that you do this language very well... it almost
feels a bit overdone, but then again, I guess it's intentional.

    Cologne regarded him with a steely gaze across the wooden
table in the kitchen of the Nekohanten.  A mountainous pile of 
carrot peelings was slowly obscuring her from view as she worked.  
"Why?"

um. What's wrong with "slowly obscured"?
     

    A series of taps, gradually decreasing in volume, echoed
through the kitchen as Cologne made her way up the steps.  Bored
without an immediate source of stimuli, Ranma rapped his knuckles
on the underside of the table in a rhythm only he knew for a few
seconds, and then began to juggle a half-dozen uncut carrots.  

I would switch that around a bit, since it reads as it being only
for a few seconds that Ranma is the only one who knows the rhythm.
Or something like that.

FIN ONE

Well, that was ... interesting, so far. Well written, as far as I
can tell, and though it promises to not really be the type of
story I like most (among His<tm> works, the dreamland ones were
never among my favorites), I do look forward to reading the upcoming
parts.

It's been too long since I read any of it for me to comment on
how well it stays close to its source(s), but then, on the other
hand, I guess by its very nature the dreamlands can appear rather
different from time to time, so...

Did I mention the language is rather skillfully crafted? :-)

---
Ronny Hedin, thark@hem2.passagen.se, http://nabiki.newberry.edu/thark/
                    "Momomoto, famous japanese, can swallow his nose."