does this hard drive use special screws? normal case screws do not work for you?
can you try pulling out a screw (holding in the power supply or an add on card) and see if that works?
There are only really two types of screws used in PCs and it has been that way for years. Once is a small width one for CDroms/floppy drives and the other is a larger width screw, usually with a hex head and philips centre. This would be on the back of the case, holding all hard drives in, holding the motherboard in and the add on cards.
You dont need any special scrws that you would have to order (lol). just go down to any computer shop and they should have a coffee can full of screws to give you for free.