The component you get the "missing component" error on is apparently related to SQLDMO.DLL, which is one of the components of “SQL Database Management Object”. The documentation for SQL Server 2008 indicated that support for SQL-DMO was going to be removed in the next version of SQL Server. It was actually removed from SQL Server 2008 too, they just maintained support for it through the SQL Server 2005 backwards compatibility components. So... for SQL 2008, you can get this component installed by searching for the download for the SQL Server 2005 backwards compatibility components and installing that package after you've got SQL 2008 on there. Then this solution works fine (we've used it for SQL 08 installs for several years).
For SQL 2012, we're going to be out of luck. The documentation for SQL Server 2012 indicates that it has been removed completely and is no longer supported. So if you’re using SQL Server 2012, this web admin solution will not be an option.