I know that you do not want to use the webservices, however maybe it is of interest anyway.
In the ASDK help file you find the information about "Creating and using proxy classes". The help file can be found in %programfiles%\Altiris\Altiris ASDK\Help and then open the .chm file. In the help file you find the information under Programming Guides --> C# Web Service Programming Guid --> Creating and Using Proxy Classes...