Hi Matt Santucci,
If the database has already been created you can create a new user with db_datareader and db_datawriter rights. If you use ASP.NET user account ( or the relevant one for Windows Vista or Windows 7) there should not be a problem to grant it with dbo rights. Then you need to use integrated security with SSPI connection.
Just to let you know we sent the same reply to your support request.
the Telerik team