How do I write information into the system registry - I need to write different twain selections inot the registry.

Hi

I have an application where I need tobe able to switch between different twain selections. At the moment I use a default delection. Does anyone know how I can take this information and write it into the registry allowing the user to auto select their chosen twain source. In mya application I need two twain sources tobe available at the same time (camera and scanner) any help apprectared.