Altium - Component outline
You can either do this in the library by adding a 3D model or an extruded body, or directly in the PCB editor. Adding models in the library is quite simple, so I'll focus on the PCB method.

To do this in the PCB tool, go to: 


  Tools > Manage 3D Bodies for Components on Board


You will see the dialog shown below. Select your component and go through the list of options in the Interactive tab. You can select more than one outline, if needed.



The image on the left shows you the current setup, while the image on the right shows you the currently selected shape. Here's what I get after selecting a few more shapes (note that the shape is no longer rectangular):