How does user mode STI minidriver enable KS device event?

I would write a user mode STI minidriver to monitor PC camera button pressed
event.
How does user mode STI minidriver enable KS device event?
I know IOCTL_KS_ENABLE_EVENT can do that, but how??
Should I use DeviceIoControl or KsSynchronousDeviceControl to send
IOCTL_KS_ENABLE_EVENT?
How do I get the associated KS object or handle of my device in user mode
STI minidriver?

Best Regards
Jack Huang