1. Select the object to position at the currently focused Viewport's center.
2.
(Option a - recommended). Press Shift-C to open the Commander. Type View Center into the Commander's edit box, followed by the Enter key, in order to execute the command. The following image depicts what should be displayed in the Commander right before you press the Enter key to execute:
or
(Option b - for Cinema 4D beginners). From the Cinema 4D Main Menu, use the Tools -> Axis -> View Center command to perform the desired operation:
The resulting outcome of the above steps is that your object should get repositioned to the currently focused Viewport's center. More precisely, it is the axis of your object that will be used to position it at said center. If your object's axis happens to lie in the middle of the object (i.e., the middle of its points), which is true for many, but not all objects, then your object itself should be positioned at the current viewport's center. If not, you may need to either adjust the object's axis independently of its points or vice versa, which is a separate question/topic (helpful tip: with the object selected in Model mode, use either the Center Axis to or the Center Object to command, respectively. Use the image above to assist you in finding these commands on the menu, if you have trouble locating them). Then reposition the (axis adjusted) object once again at the view center using the aforementioned steps or further manually tweak its position to your heart's content.
Additional note: The View Center command does not change the object's rotation or scale. It is only useful for altering an object's position (assuming that the object is not already at the view center). Primarily, this command is used to bring a "run away object," as is often the case upon initial object creation (but also after pasting from a different scene, as is the case for your particular scenario), to the center of the Viewport, making both it and its axis tool visible. This makes it easier to further refine the object's position within the confines of the vantage point offered by the currently focused Viewport.
I am hopeful that the detailed answer I've provided above is "idiot proof."