If you are using the 3Delight render engine, and don't need to use a specific shader:
To stop a whole item from casting shadows, just click off the Cast shadows property in the Parameters pane. To hide the object but still have it cast shadows, select the surface of the object to hide, double-click on !UberSurface Base.duf, then in the parameters pane set the "Fantom" property to "On".
Comments
If you are using the 3Delight render engine, and don't need to use a specific shader:
To stop a whole item from casting shadows, just click off the Cast shadows property in the Parameters pane. To hide the object but still have it cast shadows, select the surface of the object to hide, double-click on !UberSurface Base.duf, then in the parameters pane set the "Fantom" property to "On".