Using Cinema 4D 9.6 / OSX 10.4.8
Well, first create your text as explained in the Help-Manual Page 261/262.
Than select your Extrude NURBS go to Functions/Make Editable or hit the C key.
Select the Extrude NURBS and Cap 1 and Cap 2.
In the Object Manager go to Objects/Connect.
You can now delete the old Extrude NURBS and keep Extrude NURBS.1.
Here is your polygon-object.
Cheers
Nolan