If so, just hold 'z'. Moving the mouse, then, will move the container up and down along the 'z' axis.
Easier to tap the "F" key, which will cause it to fall to the next mesh that it encounters. I usually put the item on the desk, hit [F], then raise it a click or two to make sure it has a teeny tiny gap between the desk and the object.
Most of the time I work from an object palette, and ctrl-alt-click to place the object. If there are any fog effects, lights, or other areas, I always zoom in as far as I can (hold down [V] and move the mouse up/down) before doing the ctrl-alt-click. Otherwise when you put the object in, it likes to perch on top of whatever fog / light / activation box is in the view in front of the camera.