There are two ways to open these without the special screwdriver, you can use a hammer and just bust the thing open (using brute force) or take a dremel and cut a slot or Phillips head into the screw.
Since we have evolved from the cavemen i will show you how a gentleman opens these.
You will need a dremel rotary tool and fiberglass reenforced cut off wheel.
appropriate PPE (glasses, ear protection, reflective belt)
Here is some cool information for screws
Step 1: Add a slot into the top
Take your dremel tool and carefully cut a slot in to the top of the screw. You want to modify the screw head to accept the new tool as perfect as possible. If you make the slot too wide then you risk shearing off the head and ruining the screw. If you make it too narrow then you risk injuring yourself when the tool slips.
With practice its possible to cut a Phillips head into the head of the screw.