Setting the 'Show on (viewer) Panel' property for a parameter

In Crystal 2008 designer, the 'Show on (viewer) Panel' property (in the edit parameter dialog) controls whether or not the parameter is shown in the parameter panel.

However, I can't seem to find a way to control that behavior in code from the Crystal 2008 .Net SDK. Can anyone confirm this as a known limitation or point to a relevant method/property?

Thanks,

- Ido