I don't think you can use a CD or battery in a FDD slot. Even on desktops Floppy drives do not use standard IDE, instead they have a special "Floppy" port. The only thing I think you could do is use the empty space for USB hub or other stuff. You can desolder one of the USB ports off of the motherboard and solder wires to the connections, then put the circuit board from a hub in the empty floppy area.