During a recent setup of BizTalk setup, I was getting a failure that the setup could not connect to the SSODB.
I thought it was odd, because the SSODB had not been created.
It appears that the SSOSQL.dll was properly registered during the install.
To register the SSOSQL.dll, open up the Visual Studio Command prompt and path to the SSOSQL.dll directory (C:\Program Files\Common Files\Enterprise Single Sign-On) and key in regasm SSOSQL.dll