I would like to be able to use the stored procedure
'aspnet_Membership_CreateUser' directly through T-SQL code (instead of going
through .Net wrappers) because I need to automate the creation of hundreds
of users.

aspnet_Membership_CreateUser has among others the following parameters:
@Password, @PasswordSalt, @PasswordAnswer.

I assume that the @Password and @PasswordAnswer have to be encrypted using
the @PasswordSalt

I have been unable to find documentation that explains

1. how to create the passwordsalt or where to retrieve it from
2. how to hash/encrypt the password and the security answer.
  Is there another SP that does that?

Any help would be greatly appreciated.

Roberto