Hi,
Users in crm must be mapped to an AD account, but theoretically you could configure Crm to use Claims based authentication and then write your own asp.net authentication claims provider that maps the sql account to the users AD account.
To configure for claims based auth:
http://blogs.msdn.com/b/crm/archive/2011/01/13/configuring-ifd-with-microsoft-dynamics-crm-2011.aspx
Your custom claims provider have to work similar to:
http://samirvaidya.blogspot.co.uk/2012/04/downloadable-custom-claims-provider.html
It will be a complex process and you'll need to be an expert in ADFS2.0
Let us know how you get on!
Scott Durow
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