Can I choose to install the content without installing the x1 program?
Yes. You don't have to install the program data, that's on another disk anyway. When you begin to install the Additional Content disk/download version, you will come to a screen where you can even choose which items to install by placing a checkmark in the box next to the item/s you want to install, so you can choose only to install the Hollywood FX pack, if that's all you want to install.
However, since it's the Hollywood FX pack that you want to install, you will, of course, have to have D Pro installed, already. :)