Disabling hackshield in windows 64 is possible, but it will require methods that are inconvenient for one, and also INCREDIBLY difficult.
The reason behind this is the complete inability to run, and interact with rootkits in 64 bit editions of xp, vista, and 7 (as well as 8 from the beta thus far.)
Microsoft has 64 bit versions for increased performance, but also increased security. Due to the operating environment requiring certificate signing for drivers, disabled root access, etc. This promotes the usability of the "personal computer" towards it's goal of a home computing device (which computers were NOT designed to be in the first place.)
The best option you would have is to run a Virtual System using windows 32bit and try it within there.
Another option you have is a simple one, installing an operating system to a large enough flash drive to support both it, and the game, and performing a "dual boot" by booting from the USB device when the system powers on by enabling the option (if it isn't already) in the bios (typically F2, F10, or DEL.)
The third, and most difficult option, is dual booting operating systems off multiple disks in your computer.
This is going to vary in complexity, and method depending on your computer.
Good luck
Dracconus