I am not familiar with the scd, but soy it toxic, and those who know it do not promote it. In general, it's best to stay away from soy.
I know that's initially crazy to hear, but encourage you to do some reading. Here's some links:

http://www.soyonlineservice.co.nz/

http://www.thedoctorwithin.com/index_fr.html?content=articles/index...
(read the article titled "the magic bean? soy-tainly not!")

Read this entire thread here at curezone:
//www.curezone.org/forums/m.asp?f=461&i=2173

This post, as well:
//www.curezone.org/forums/m.asp?f=10&i=331

In Breaking the Vicious Cycle, Elaine Gottschall talks about the way different carbohydrates react in the digestive track. Sorry I don't remember the specifics, but the carbs in soy must be among those that have a negative impact on those of us with GI track issues.

This is a different matter than what the other poster was saying. But I am also of the mind that soy ought to be avoided except in its fermented forms.

Actually on their website they mention that fermented soy (tempeh, miso, tamari) are okay after symptom haves subsided. Usually soy sprouts are okay, too. But most soy foods should be avoided for many reasons. I avoid soy because the isoflavones can damage the thyroid and I have a family history of thyroid problems.