Below is a post from the RisusTalk List. I include it here, with the author's permission, as another take on how to handle a Call of Cthulhu to Risus conversion:

from	JerryA!<jerry-yahoo@thehutt.org>
reply-to	risustalk@yahoogroups.com
to	risustalk@yahoogroups.com
date	Jan 2, 2007 7:01 PM
subject	[risustalk] Risthuloo
mailed-by	returns.groups.yahoo.com

A week or so ago, there was some discussion about how to simulate
Call of Cthulhu's Sanity mechanism in Risus. Various bolt-on
mechanisms were presented. Please humor me while I present the
following for your consideration. No bolt-ons required. It's just one
interpretation of the Zen of Risus.

Start with the following 2 tenets:

1. Just as characters are living, breathing, and evolving entities,
so are their clichés.
2. Target Numbers (TN) are arbitrary.

Take these two things together and season with the following thought:
The number of dice in a given cliché are how much of themselves a
character can give, and not a direct reflection on how proficient
they are. Sometimes it doesn't matter how talented, smart,
experienced, good-looking, etc. you are--you'll be too pooped to
handle stuff you normally could. Proficiency in Risus is contextual
and handled as a case-by-case melding of the 2 tenets.

So, how do these thought nuggets apply to play? Let's take a look at
our sample hero and walk him through two scenarios.

Wayne Folsom
Well-Travelled Occult Detective (4)
Former Criminal Mastermind (3)
Zen Coffee-Lounge Artiste (3)
Gambler (1)

Some Background: While perusing his favorite used book store, Wayne
happens across what appears to be a genuine copy of the 1845
translation of Nameless Cults. What a find! Haggling with the guy who
"Runs A Bookstore For Weirdos and Goths (5)" he picks up the book,
but for more than he originally wanted to spend. Such is life,
besides this will make a great addition to his summer reading list.

Anyway, Wayne pops the book on the shelf. He'll peruse it when he
returns from this zombie-infestation case he was hired to look into.

Scenario 1:

Wayne returns a week later thinking that it shouldn't have been so
tough to overcome a collection of bones. Maybe he should get around
to reading some of those books that he's picked up and see if he
can't learn better ways of dealing with future nasties.

Wayne spends the next 3 months pouring over the dark texts as his
disposal (including the one he borrowed from Dr. Wu ages ago). For
purposes of combat, the GM decides that Wayne has to beat 3
increasingly difficult TN rolls (18, 22, and 28) using the "Well-
Travelled Occult Detective (4)" cliché. Wayne makes 2 of the 3 rolls.
The GM decides that Wayne has gained much knowledge but is
temporarily suffering from horrifically bad dreams (tm) and a slight
case of paranoia. Nothing earth-shattering or permanently
debilitating, but enough to make him think twice before delving again
so deeply into such volumes.

For the purposes of game play, Wayne's "Well-Travelled Occult
Detective (4)" cliché now becomes "Well-Travelled Occult Detective
Who Knows Too Much (4)". Now when Wayne needs to engage in some clue-
finding, glyph deciphering, Byakhee calling, etc. the GM reduces the
TN. Conversely, the GM will up the TN for Wayne not to wet himself
the next time he runs into an avatar of Nyarly.

As for the bad dreams and such, the we'll bump up the TN for
appropriate tasks for the next 2 or 3 sessions.

There, we've now covered Sanity, Cthulhu Mythos, and Temporary
Insanity without adding any new mechanics. Nifty, huh?

Scenario 2:

Wayne needs money badly (that's what happens when you take a few
months off to read). Against his better judgement he joins his friend
Sir Walter Eden-Smythe an a little South Seas expedition. Too much
money to pass up for taking a cruise, keeping a friend company, and
writing a travelogue of their journey.

Long story short, on the island they run into Cthulhu ("Great Old One
Who Lies Dead Dreamin' But Is Awake Right Now (9)"). After a long and
ugly battle, Wayne escapes by the skin of his teeth. How bad off is
he? All of his clichés are at 0 except for "Zen Coffee-Lounge
Artiste" which is at 1. He's alive, but barely clinging on. Recovery
is going to be a slow, painful process that isn't complete until
Wayne figures out how to deal with the shock of what he's witnessed
and survived.

Fast forward 6 months. We run into Wayne who seems physically fit,
yet somehow different and transformed after his harrowing three-hour
tour.

Wayne Folsom
Well-Travelled Occult Detective Who Knows Way Too Much (4)
Former Criminal Mastermind With A Texas-Sized Liver (3)
Zen Coffee-Lounge Artiste (3)
Gambler (2)

As you can see, Wayne's turned to the bottle to dull the pain. The GM
also decides that any encounter with seafood has an automatic TN of 30.

Voila, there's Long-Term Insanity (or poorly dealing with it) and a
possible phobia. Wayne had the option of being committed, but the
GM's a bastard and wasn't done toying with Wayne quite yet.

The beauty of Risus is that it can be flexed in all types of crazy
ways without needing additional mechanics. Please let me know what
you think of this. And remember, there's no wrong way to play!

--Jerry