actaully I am owner of Vertex 3 and I'm surprised the v4 support AES256. I always believed that OCZ supported the simpler 8 char password .
but as far as I understand the way to access that disk is when booting your laptop it should pop up the BIOS question for the HDD password (just like boot password)
so the question is , at boot time, does your BIOS asks you for the HDD password ?
if not , there is always a possibility to use hdparm from command line