In Cinema 4d you can assign more than one material to a single object. For this example I’m going to use a simple polygon object.

Step 1;

Create a polygon sphere, then click on the "Make Object Editable" or hit "C" on your keyboard. Then select the faces of the top half of the sphere.

Step 2;

Then go to Selection, and Set Selection. Go ahead and give it a name, then deselect the object before making the next selection.

You'll notice that a triangle appears next to the object in the Layer menu that represents the selected polygons.

Now repeat the process for the bottom half of the sphere.

Step 3;

Now create two new materials and give them whatever color or textures you want. Then select the first triangle and click on the "Select Polygons" button. The polygons that you previous selected should be highlighted now.

Step 4;

Next right click on the material you want to assign to the selected polygons and hit "Apply." Now the material should only be applied to those polygons selected.

Now repeat the process for the other half of the sphere and render out your image. What you should get is an object with 2 separate textures applied to it like the image below.