You can use a Cognos SDK application that was written in Java with an Active Server Page (ASP). With your Cognos 8 installation you have the option to add the Cognos SDK examples and sample files. Besides using C# you will notice that the majority of the SDK examples are Java based.
You have two options:
A. Use the Visual Studio.NET IDE to convert the Java class to C# class files and attempt to rework the SDK code
B. Use the existing Java class as-is and create a COM object.
You can read also these articles for a simple how-to example: http://www.4guysfromrolla.com/webtech/080999-1.shtml
http://j-integra.intrinsyc.com/support/com/doc/asp_java/ASP_to_Java_Program_DCOM.html
