how to use reflector service in windows CE 7.0

I am using platform builder for WEC 7.0 development. + I want to know how can i use reflector service in my user application to call user mode driver function. Anyway we can use some in built API’s like xxx_open xxx_close xxx_read xxx_write etc. But what if i write my own function in kernel driver and call it from user mode application? how to use reflector?