Video power management

Hi,
I’m trying to create the user mode application that turns my display and graphic adapter off/on. Assuming that OS is XP (thus, making IOCTL_VIDEO_SET_POWER_MANAGEMENT obsolete) and ACPI is disabled, how can I do it?
As far as I could see, there is HwVidSetPowerState entry in newer miniport model, but I don’t understand how to invoke this entry point from the user mode application. Is it still through DeviceIOControl with the obsolete code?
Thanks in advance,
Alex.